EP2243340A1 - Methods for diagnosing and automatically controlling the operation of a particle accelerator - Google Patents
Methods for diagnosing and automatically controlling the operation of a particle acceleratorInfo
- Publication number
- EP2243340A1 EP2243340A1 EP09706715A EP09706715A EP2243340A1 EP 2243340 A1 EP2243340 A1 EP 2243340A1 EP 09706715 A EP09706715 A EP 09706715A EP 09706715 A EP09706715 A EP 09706715A EP 2243340 A1 EP2243340 A1 EP 2243340A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- accelerator
- successfully
- particle beam
- particle
- vacuum chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H7/00—Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H7/00—Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
- H05H7/001—Arrangements for beam delivery or irradiation
- H05H2007/008—Arrangements for beam delivery or irradiation for measuring beam parameters
Definitions
- Particle accelerators generally are grouped into different categories according to their fundamental concepts:
- Circular accelerators that recirculate the beam of particles through a radio frequency cavity to reach a desired energy such as a cyclotron, synchrotron, microtron, racetrack microtron or RhodotronTM .
- the accelerator may have a vacuum chamber that is annular or toroidal in shape and which serves as the accelerator beamline.
- the beamline has an electrically conductive part and an electrically non- conductive part that serves as an acceleration gap.
- a magnetic field that is present in the region of the vacuum chamber controls the motion of the beam within the vacuum chamber.
- the accelerator has two very distinct electromagnetic field regions.
- Disclosed are methods of controlling the operation of a particle accelerator comprising: injecting a particle beam into the accelerator; performing at least one injection phase diagnostic measurement; based upon the at least one injection phase diagnostic measurement, determining if the particle beam has been successfully injected; upon the particle beam not having been successfully injected, varying at least one injection phase control action, and repeating the process; upon the particle beam having been successfully injected, performing at least one acceleration phase diagnostic measurement; based upon the at least one acceleration phase diagnostic measurement, determining if the particle beam has been successfully accelerated; upon the particle beam not having been successfully accelerated, varying at least one acceleration phase control action, and repeating the process; upon the particle beam having been successfully accelerated, performing at least one use phase diagnostic measurement; based upon the at least one use phase diagnostic measurement, determining if the particle beam has been successfully used; upon the particle beam not having been successfully used, varying at least one use phase control action, and repeating the process; and upon the particle beam having been successfully used, further operating the accelerator.
- the particle accelerator may be an electron accelerator, the particle accelerator may be a localized curl accelerator, and the particle beam may be injected by an electron gun.
- Use of the particle beam may comprise extraction of the beam or the beam impinging upon an internal target.
- An electric field may be imposed upon the beam to perturb its orbit by the application of voltage across at least a pair of internal electrodes.
- Figure 1 shows one embodiment of a system illustrating details of an accelerator with a power supply disposed across a non-conducting gap of a vacuum chamber for use with certain of the diagnostic methods and apparatus disclosed herein;
- Figure 2 shows an approximate equivalent circuit of the accelerator of Figure 1
- Figure 3 A shows one embodiment of a system similar to the system of Figure 1 and having a vacuum chamber with a rectangular cross-section;
- Figure 3B shows a cross-sectional view of a portion of the system of Figure 3A, illustrating an embodiment of diagnostic apparatus
- Figure 4 A shows another embodiment of an accelerator with diagnostic apparatus, including a current sensor for detecting the current in the power supply leads;
- Figure 4B is a schematic of a circuit of a current sensor
- Figure 5 is a flow chart illustrating an embodiment of the accelerator control methods disclosed herein.
- the exemplary localized curl accelerator referenced above uses the governing rules of Maxwell's equations in a novel approach that cannot be equated with methods generally used to accelerate particles which are discussed in standard texts on this subject (see for example: M. S. Livingston and J. P. Blewett, "Particle Accelerators ' ", McGraw Hill Book Company, Inc., New York, 1962).
- the essential elements are: 1.) A magnetic core that can accommodate a time varying B field;
- a power supply that can provide suitable voltages.
- the diagnostic elements may be matched to the dynamical behavior of the accelerator and its electric and magnetic features as well as the nature of the particles being accelerated.
- the success of injection, capture and acceleration to final beam energy may require monitoring and control of the beam parameters at several stages of the acceleration process.
- the monitoring methods may indicate the quality of the parameters of the beam such as energy and intensity during different stages of the process.
- the diagnostic elements may be designed in accordance with the elements of the accelerator itself and the nature of its components and their operation.
- FIG. 1 is a schematic 100 of an embodiment of an exemplary localized curl accelerator, for use with the diagnostic techniques disclosed in U.S. Patent Application Ser. No. 12/351241, "Diagnostic Methods And Apparatus For An Accelerator Using Induction To Generate An Electric Field With A Localized Curl," by William Bertozzi and Robert J. Ledoux.
- a vacuum chamber 104 serves as a beamline and has an electrically conductive portion 106 and an electrically non-conductive portion that will be referred to as nonconducting gap 108.
- the vacuum chamber 104 may be generally tubular in cross-section (circular or rectangular, or other cross section) and may be toroidal in form, such as the circularly annular form illustrated or may have some other closed path connection that permits cyclic/circulating passage of a beam within.
- a cutaway 114 provides a view of a beam of charged particles 116 traveling within the vacuum chamber 104.
- the beam 116 is for example (not limitation) an electron beam and has one or more electrons moving, for example, in the direction indicated by the arrow.
- the cutaway 114 is for illustrative purposes only and does not represent an actual opening in the vacuum chamber 104.
- the non-conducting gap 108 has a gap length d 110.
- the conductive portion 106 of the vacuum chamber 104 has a wall thickness w 112.
- a magnetic guide field 134 is a B-field and guides beam particles in a beam 116 through the vacuum chamber 104 along a closed cyclic path.
- the magnetic guide field 134 is only indicated schematically as a single flux line, but it is recognized that the magnetic guide field may be complex, may be generated by multiple magnetic elements (not shown) and may pass through multiple or all parts of the vacuum chamber 104 to effectively guide and/or focus the beam 116.
- the vacuum chamber 104 surrounds a portion of an induction core 102.
- the conductive portion 106 of the vacuum chamber 104 has two ends 118, 120 that are separated by the non-conducting gap 108.
- Power supply 122 has a first terminal 124 that may be a positive terminal and which is connected to end 120.
- Power supply 122 has a second terminal 126 that may be a negative terminal and which is connected to end 118.
- Power supply 122 provides a voltage V that may be a time varying voltage and that may oscillate and reverse polarity periodically in a square wave fashion or with some other suitable waveform.
- This particle is guided around the induction core 102 inside the vacuum chamber 104 by an appropriate magnetic guide field 134.
- the particle experiences no retarding fields in the vacuum chamber 104 because all fields (except for the static magnetic guide field as discussed below) are zero except for those induced on the walls by the charge of the particle itself.
- As the particle travels around the induction core 102 it reenters and traverses the non-conducting gap 108 in the vacuum chamber 104 and its energy is increased by qV again. If it makes n turns (herein the terms "turn” or "turns,” when referring to beam or particle motion, means a complete circuit, cycle or revolution of the vacuum chamber) of the vacuum chamber 104 it gains a total energy nqV.
- E is the electric field in the vacuum chamber 104 and dl represents the path length differential for the beam path (bold quantities are used to represent vectors).
- an induced image charge on the inner surface of the conductive portion 106 of the vacuum chamber 104 forms current Ii 132 and travels along the inner surface in the same direction as the path of the particle(s) in the beam 116.
- Current Ii 132 is equal to the rate of flow of charge of the particle(s) in magnitude and opposite in sign.
- this image charge is positive.
- the particle(s) in the beam 116 reaches the end 118 of the conductive portion 106 at the non-conducting gap 108 it simply crosses the non-conducting gap 108 in the vacuum and gains energy q ⁇ .
- the induced image charge (and thus the current Ii 132) has no alternative but to come to the outer surface of the conductive portion 106.
- the current Ii 132 travels through electrical leads 128 and through the power supply 122, which has an ideally zero impedance.
- the current Ii 132 resulting from the image charge flows through the power supply 122, electrical leads 128, and enters the inner wall of the conductive portion 106 of vacuum chamber 104 at the end 120, adjacent the nonconducting gap 108 with the voltage +V and exits at the inner wall of the conductive portion 106 at the end 118, where the voltage is zero, and returns to the power supply 122.
- the image charge flow provides an additional current Ii 132 flow into the power supply equal to the current flow of the beam 116.
- the image charge flow is an image current.
- the power supply provides power to energize the induction core 102 and additionally it provides power to the beam 116 via this coupling with the image charge or image current.
- ⁇ is the skin thickness.
- the value of ⁇ depends on the resistivity of the conductive portion 106 of the vacuum chamber 104 and the frequency of the external relevant electromagnetic fields considered. As an example, at 2 KHz and for copper, ⁇ is approximately 1.5 mm.
- the non-conducting gap 108 still causes the flow of the image charge current Ii 132 from the +V side of the power supply 122 into the inner surface of the conductive portion 106 of the vacuum chamber 104 and the flow of the image charge current Ii 132 out of the inner surface of the conductive portion 106 into the low potential side of the power supply 122.
- the Ohmic resistance to the flow of the current Ii 132 and the current Io 130 are no longer zero (as in the idealized situation discussed above) in the conductive portion 106, but can be evaluated using standard expressions of current flow through a medium with resistivity p with the current distributed in the skin thicknesses of the inner and outer surfaces as described above.
- these losses may be low compared to power consumption by other elements.
- Figure 2 is an approximate equivalent circuit schematic 200 of the localized curl accelerator shown in Figure 1.
- the inductance of the one-turn coil formed by the conductive portion 106 the vacuum chamber 104 around the induction core 102 is represented by the symbol L in schematic 200.
- the energy dissipation of the outer surface current Io 130 due to finite conductivity of the conductive portion 106 is represented by the current, Io, flowing through the resistance Ro in schematic 200. This current, Io, is governed by Equation 1 :
- V - Ldlo/dt - I 0 R 0 0 (Equation 1 )
- the energy dissipation of the induced image current Ii 132 in the inside of the conductive portion is noted by the current, I 1 , flowing through a resistance given by the symbol Ri in schematic 200.
- the symbol CBP denotes the beam coupling of the beam 116 to the power supply 122 via the induced image current Ii 132 on the inside of the conductive portion 106.
- the image current Ii 132 is supplied by the power supply 122 via the beam coupling CBP through the non-conducting gap 108.
- the total power supply 122 current is:
- the total current from the power supply 122 is the sum of the current Io 130 exciting a magnetic flux in the induction core 102 and the current I B due to the beam 116.
- the power supply 122 supplies energy to the magnetic field in the induction core 102 and to the beam 116. If the beam 116 is not present, only the magnetic energy is supplied.
- the losses due to the dissipation in Ro and Ri are small compared to the dissipation in the magnetic induction core 102 due to hysteresis and internal currents and therefore the Ohmic losses may be neglected.
- the dissipation in Ri causes a decrease in the energy gain of the circulating beam 116. In general this decrease is much smaller than the qV beam energy gain for each turn and may again be neglected in terms of beam dynamics except in evaluating the final particle energy.
- the induction core 102 forms a complete magnetic circuit.
- the vacuum chamber 104 provides an evacuated region for the beam 116 to circulate about the induction core 102.
- the beam 116 is guided by magnetic guide field 134 that constrains all beam orbits to lie within the confines of the vacuum chamber 104.
- the vacuum chamber (though not necessarily of circular shape) 104 encircles the induction core 102.
- the current Io 130 flows on the outer surface of the conductive portion 106 of vacuum chamber 104.
- the non-conducting gap 108 has a power supply 122 connected across it.
- the currents Io 130 and I B current Ii 132 flow out of the first terminal 124 of power supply 122 (positive terminal) and into the second terminal 126 of the power supply 122 (negative terminal).
- the power supply 122 presents a voltage V across its terminals 124, 126 as discussed above and the characterization of the first terminal 124 as + and the second terminal 126 as - only implies that the + is at a higher potential than the - terminal when V is positive.
- An electron gun for example, may be present at an inner radius and may produce a beam of particles (1) that are synchronized with the application of the voltage V to the non-conducting gap of the accelerating cavity and (2) that lasts for a duration determined by the application at hand.
- this may be a short burst of particles, such that the burst has ended before the leading edge completes one circuit of the vacuum chamber.
- this may be a long burst of particles lasting as long as the sweep of the induction core from -Bc to +Bc, where Bc is the maximum field in the induction core; in some cases it may be desirable that Bc may approach or reach core saturation.
- the critical period for injection and capture may encompass a few to a dozen circuits or turns of the vacuum chamber by the injected beam, such that if those circuits have been successfully negotiated the beam is considered captured; if this number of circuits were not achieved it would be important to understand where and when the injected beam had been lost.
- the beam progresses to be accelerated to full energy.
- a portion of the beam or the entire beam may be lost on its way to gaining the final energy. Knowing when and where this loss occurs is essential to diagnosing the problem and developing adjustments to mitigate or correct the situation.
- Extraction of the beam at full energy may also require special magnetic and/or electric signals to be applied to the beam to kick it out of a stable orbit to be captured by an extraction system.
- the beam may be important to know when to initiate that process.
- having a signal or signals that establish that the beam has reached full energy is also important.
- the transducing element consists of conducting electrodes that do not intercept the beam, placed at different locations in the chamber out of the path of the particle beam.
- Such an exemplary embodiment is shown in Figures 3A and 3B.
- FIG 3 A is a schematic 300A illustrating a system of an exemplary localized curl accelerator similar in construction and operation to that shown in Figure 1 , except that the vacuum chamber 304 is (for example, not for limitation) rectangular in cross-section.
- the vacuum chamber 304 serves as a beamline and has an electrically conductive portion 306 and an electrically non-conductive portion referred to as non-conducting gap 308.
- the conductive portion 306 of the vacuum chamber 304 has two ends 318, 320 that are separated by the non-conducting gap 308, which is used as an acceleration gap.
- the joints between the ends 318 and 320 of the conducting portion 306 and the non-conducting gap 308 portion are sealed by conventional vacuum sealing techniques.
- An imaginary cutting plane 330 defines the location of a cross-sectional view in the direction A-A is indicated cutting the electrically conductive portion 306 of the vacuum chamber 304.
- the accelerator has an inductive core 102.
- Figure 3B is a cross-sectional view 300B of a portion of the system of Figure 3 A, showing the conductive portion 306 of the vacuum chamber 304, taken at the cutting plane 330 (Figure 3A) looking in the direction A-A (of Figure 3A) and showing additional detail not shown in Figure 3A.
- the conductive portion 306 of the vacuum chamber 304 encloses a beam 316 traveling into the plane of the paper and indicated in this view by its cross-sectional profile (elliptical, for example).
- One or more conducting electrodes 336 are mounted within the conductive portion 306 of the vacuum chamber 304.
- the conductive electrodes 336 are isolated electrically from the walls of the conductive portion 306 of the vacuum chamber 304 by conventional means (not shown) and are provided with external connections through the walls of the chamber.
- the conductive electrodes 336 may be multiple and may be arranged in a regular array (as shown) or another pattern as may be desired and may be arranged on one or more sides of the beam 316.
- Each of the conductive electrodes 336 has an electrical lead for connection.
- Each lead may pass through the conductive portion 306 of the vacuum chamber 304 through a single-lead hermetic feedthrough 338 as indicated for leads at the top of the conductive portion 306. In that case leads 342 may connect to instrumentation 350 for monitoring and analyzing signals from the conductive electrodes 336 conveyed by the electrical leads 342.
- the leads may be bundled into a cable 340 and pass through the conductive portion 306 of the vacuum chamber 304 through a multi-lead hermetic feedthrough 344 as indicated for the leads at the bottom of the conductive portion 306.
- the leads in cable 340 may also connect to instrumentation 350 for monitoring and analyzing signals from the conductive electrodes 336.
- instrumentation is designed so that the conductive electrodes 336 may each present high (relative to other conductive paths of the system) resistive impedances to current flow.
- Each conductive electrode 336 will receive an induced voltage, Vi, created by the image charge, q, from the beam passing nearby.
- This Vi will be induced according to the standard rules of electromagnetism and will depend on q, distributed capacity and the impedance of the circuit.
- This Vi presents a signal that a certain amount of beam charge has reached a specific location in the vacuum chamber 304 at a specific time.
- Instrumentation 350 may consist of purpose-built instruments and/or may comprise a general purpose microprocessing system.
- This diagnostic scheme provides the following information on accelerator performance:
- a beam charge pulse that lasts less that the time for one turn will show up (depending upon the electrode placement and spacing) as a signal on one or a few of the conductive electrodes 336 that couple via the induced charge.
- These signals convey information to determine the position of the beam 316 as it orbits around the vacuum chamber 304, and as the pulses are counted they may establish the number of turns (circuits of the vacuum chamber 304) having been executed and the losses from each turn.
- the amplitude oscillations of the beam about the equilibrium orbit may be determined as well, and the changes in orbit position as the beam is accelerated on each pass through the accelerating region at the non-conducting gap 308 of the vacuum chamber 304.
- the number of circuits or turns is determined, and thus the energy of the beam may be known at any time because the energy gain is qV for each turn (where the charge of the particles is q). Similarly, it can be established when the beam 316 has reached the full energy.
- the correlation of energy and conductive electrode 336 position can also be used as a diagnostic method. If the beam is lost in some region of the vacuum chamber 304, this position may be determined as may be the onset of beam loss by the changing amplitude of the signals for successive turns.
- the beam pulse may be longer than in the above case, as by injection continuing until the full energy is reached for the first particles injected.
- the progression of the beam 316 through the acceleration process still can be monitored by the timing and amplitude of the signals induced on the conductive electrodes 336. This allows monitoring the entire acceleration process with an accelerating chamber full of charge.
- the beam 316 will have components at all energies from that of injection up to that of extraction or use with an internal target and different conductive electrodes 336 will have signals induced from beam components at different energies. This allows the additional monitoring of the effects of the interaction of different components of the beam via space charge effects and the generation of ions in the residual gas in the vacuum chamber 304.
- the beam pulse may be longer than the time required for acceleration to full energy in order to achieve higher beam duty cycle.
- the signals on the conductive electrodes 336 will allow a determination of the quality of operation during the full duty cycle and will provide an opportunity to control and adjust beam quality.
- Figure 4A is a diagram of a system 400 comprising an exemplary localized curl accelerator similar to that in Figure 1 with the embodiment of a current sensor for detecting the current flowing to the power supply 122 for the accelerator and with sensors for various other beam characteristics. It also includes control means for controlling the accelerator.
- the accelerator of system 400 is similar to the accelerators of Figure 1 and Figure 3 A. Items with like reference numbers to those in Figures 1, 3 A, and 3B are like items with like functions.
- the vacuum chamber 104 may be generally tubular (of circular cross-section as shown in Figures 1 and 4 A or of rectangular cross-section as shown in Figures 3A and 3B, or having another other cross-sectional shape) and may be circularly annular as illustrated or may have some other closed path connection that permits cyclic/circulating passage of a beam within in a circular path around a portion of the induction core 102.
- a cutaway 114 provides a view of a beam of charged particles 116 traveling within the vacuum chamber 104.
- a transducing element may measure the current flowing to the power supply 122 from the conducting portion 106 of the vacuum chamber 104.
- the currents Io 130 and I B current Ii 132 flow out of the first terminal of power supply 122 (positive terminal) and into the second terminal of the power supply 122 (negative terminal).
- the current sensor 402 may be connected, for example, at connection points C and D.
- This current sensor may be a low impedance resistor in the power supply 122 electrical leads 128; the voltage across this resistor would indicate the current passing through the electrical leads 128. (An internal resistance of the power supply 122 with suitable connections, may serve the same purpose).
- a signal representing the current I may be generated by the current sensor 402 and transmitted by electrical lead(s) 404 to instrumentation 406, which may consist of purpose-built instruments and/or may comprise a general purpose microprocessing or other computing system for analysis of the current I and for extracting and processing additional information and for decision making.
- One or more conductive electrodes may be included within the conductive portion 106 of the vacuum chamber 104 at one or more distinct locations for sensing characteristics of the beam 116 and may consist of one or more arrays of conductive electrodes (not shown, but similar to electrodes 336 in Figure 3B) for example.
- Conductive electrodes within the conductive portion 106 of the vacuum chamber 104 may connect through one or more hermetic feedthroughs 344 (two shown for example, not for limitation) at one or more locations (shown for example, not for limitation) and through cable 340 to instrumentation 350.
- Instrumentation 350 and instrumentation 406 may connect through cables 408 to controller 410.
- Controller 410 may consist of purpose-built control elements and/or may comprise a general-purpose microprocessing or other computing systems(s) making accelerator control decisions and executing accelerator control algorithms for accelerator control. Controller 410 may convey control commands to control elements 414 via a cable 412 (electrical, optical, etc.) and may include display and other communications means.
- Control elements 414 may comprise power supplies (including without limitation power supply 122), magnet control system (including without limitation control of magnets for producing guide field 134), actuators, and other accelerator control elements as are conventionally employed (but not shown in Figure 4A) in accelerator control and as will be well known to those skilled in the art. Some examples of other such accelerator control elements may include, without limitation, elements for beam injection and extraction (or use with an internal target), cooling and temperature control elements, guide field magnets, vacuum system controls, acceleration controls, controls to remove ions generated by the beam, etc. Control elements 414 may have direct linkages 416 to elements of the accelerator system 400 that may include, without limitation, electrical linkages, magnetic linkages, optical linkages, mechanical linkages, etc.
- FIG. 4B is a schematic 450 of a circuit of an alternative current sensor 402 embodiment that may be employed in system 400 or a similar system.
- the current sensor 402 is a transformer 452, for example a toroidal transformer, that senses the magnetic field caused by the current flow I from the power supply 122.
- the voltage from the transformer 452 depends on the time rate of change of the current I in the electrical leads 128 to the power supply 122.
- Other methods for sensing the current will be known to those experienced in the art and they are intended to be encompassed in this disclosure.
- the signal available from one of these current sensors may provide the following diagnostic information:
- a beam charge pulse that lasts less that the time for one turn will show up as a current pulse in the power supply lines for each revolution ("turn") of the beam. By counting these pulses the number of turns successfully executed can be determined. The beam energy will be given by the number of turns executed and the voltage V. By measuring the integrated charge of each pulse the beam loss for each turn can be determined. The success of the injection process, the capture process, the acceleration process and the extraction or internal utilization process can be monitored for a short beam charge pulse. If there is a loss of beam, the number of turns the beam has executed (and consequently the beam energy) as well as the position of the beam where the loss is taking place can be determined.
- the beam may be injected continuously over the time necessary for the maximum energy to be achieved by the first particles injected.
- the current from the beam grows as the number of revolutions of the beam increases.
- the current in the power supply lines due to the beam grows accordingly with time. By monitoring the current as a function of time, the condition of the beam at each turn, at each radial position and energy can be monitored.
- the beam may be injected continuously over a time greater than that required for the maximum energy to be achieved. In this case the current from the beam grows as the number of revolutions of the beam increases.
- the current stops growing as the fully accelerated beam is extracted (or as, for example, an internal beam target is used).
- the current in the power supply lines due to the beam grows accordingly with time and reaches a stable value. By monitoring this current as a function of time, the condition of the beam at each turn and energy is monitored.
- the effective duty cycle of the beam is determined.
- the signals from the current in the lines to the power supply will allow a determination of the condition of the beam as a function of position, time and energy and the correlations will allow a determination of the same effects discussed above for the signals from the conductive electrodes 336 ( Figure 3B).
- the diagnostic measurements discussed above may detect the particle beam and/or the power supply current I and may provide knowledge of:
- D3. The radial location of the beam after one turn; D4.
- the methods of detection discussed earlier provide signals about the number of beam turns accelerated, and the condition of the accelerated beam at differing locations in the accelerator, at differing times during acceleration and for different beam intensities.
- the control actions that are available to improve and automatically control the accelerator operation consist of adjustments to: Vl.
- VlO Electric and magnetic field elements to perturb the orbits of the particles during acceleration and extraction or use with an internal target
- VIl The voltage of the power supply that connects to the vacuum chamber and is responsible for providing the beam acceleration
- V12. The voltages on elements in the vacuum chamber used to remove ions generated by the beam.
- control actions may be taken to ensure proper operation of the accelerator and to optimize the number of successful turns of the beam and the beam current at extraction or other use. They may be used singly or in combination.
- the system parameters may be adjusted as part of a feedback loop to optimize extracted or internally utilized beam current and emittance or they may be set partially or even completely manually in distinct steps of operation.
- the accelerator is assumed to be an electron accelerator of a design such as that discussed above and the beam injection means is assumed to be an electron gun. Sl. The vacuum quality in the vacuum chamber is compared to the nominal allowed operational values.
- the power supply voltage is checked by comparing it to predetermined desired values.
- the field established in the induction core when the power supply is pulsed is determined (either by measurement or by calculation based on a L and I) and compared to predetermined desired values at three or more times: start of cycle; middle of cycle; and end of cycle.
- the electron gun is checked for proper heating of the filament and emitter.
- the guide field magnets are powered to predetermined currents in the magnet coils or they are powered to establish predetermined guide field patterns in the vacuum chamber.
- the injection voltage is turned on to a predetermined value.
- the emitted current from the electron gun is measured and compared to predetermined values.
- the accelerator is ready to be operated to produce an accelerated beam.
- the preset values may have been determined by computation of beam orbits and/or by previous measurements and successful accelerator operation. If any preset value is not possible then the controller may present an alarm with a summary of the results.
- a flow chart 500 for an embodiment of an automated start-up and operational procedure for the exemplary localized curl accelerator is shown in Figure 5. (It will be understood that this embodiment may also be utilized with other accelerator designs as appropriate, if necessary with modifications to conform to specific accelerator characteristics as will be understood by a person of skill in the art.) An embodiment of an automated start-up and operational procedure of the accelerator using the diagnostic measurements D(j) and control actions V(i) is illustrated in the flow chart 500. Of course, other diagnostic measurements and control actions may be accommodated as well.
- the sequence may be programmed to optimize a beam intensity (that is, the beam current I B ) at some specific location in the vacuum chamber or after a specific number of turns of the beam (although other variables may be optimized) and to follow the beam to extraction or use with an internal target with a final optimization of the beam intensity.
- This procedure may be used to establish the predetermined parameters used to establish the initial tune up described above. (Hereinafter, beam extraction and use of the beam with an internal target may collectively be referred to as "beam use.")
- the effect of variations of a control action V(i) on a diagnostic measurement D(j) may be compared in decision steps 506, 512, and 518 to predetermined or calculated values that may be stored in a lookup table of results for beam intensity or beam current, number of turns, energy, extracted or internally utilized beam and other characteristics that establish proper and intended operation.
- This procedure may use predetermined algorithms that make the comparisons in the lookup table and correlate the different D(j) and the sequence order for the adjustments. These algorithms may be established by computation and modeling and by experiment from actual accelerator operation, thus accounting for particular operational behaviors.
- the term "optimize” may refer to maximizing the beam intensity at a location relevant for the diagnostic D(j) by increasing or decreasing a parameter V(i).
- a false local beam intensity maximum (or maximum in another characteristic) may be achieved and this may be investigated by random variations of the sequences for the V(i) and the correlations in different D(j). This feature may be part of the predetermined algorithms.
- the procedure disclosed in flow chart 500 may include sequentially, the startup process 502 and three distinct sub-processes indicated as feedback loop I 524, feedback loop II 526, and feedback loop III 528.
- the startup process 502 includes for example such normal initiation steps as S1-S7.
- the process of feedback loop I 524 controls the initiation of operation from preparation for first beam injection through successful completion of a first complete turn of the beam with optimized beam intensity and position at completion of the first turn of the beam.
- this feedback loop may be extended to encompass an additional number of turns, sufficient to ensure that the beam clears the injection gun or passes another similar milestone.
- the process of feedback loop II 526 controls operation from completion of the first successful complete turn of the beam (or from completion of some predetermined greater number of turns) through obtaining satisfactory beam properties up through first satisfactory beam extraction from the accelerator or first satisfactory use of the beam with an internal target (collectively, "first satisfactory beam use").
- the process of feedback loop III 528 controls operation from first satisfactory beam use through optimization of the extracted beam. Following optimization of the used beam, there follows a step 522 of continued operation and use of a stable extracted or internally used beam using control parameters established by the previous processes. It is to be understood that in each feedback loop the value of one or more measured diagnostic quantities may be compared to desired or nominal values for a nominal beam having completed the same number of turns or being at the same stage of acceleration as the actual beam.
- the first feedback process disclosed in Figure 5 is shown by the first feedback loop (Feedback Loop I 524) of the flow chart.
- Step 504 some or all of diagnostic measurements D1-D4 may be made. (Hereinafter, measurements D1-D4 shall be referred to as "injection phase diagnostic measurements.")
- decision step 506 it may be determined if the beam has successfully executed a first turn of the accelerator (or optionally if it has successfully executed an additional number of turns, as discussed above). Successful completion may be based on the beam completing the required number of turns, or may also be based upon the beam having measured characteristics that meet predetermined nominal values or thresholds.
- this response may activate a retuning of the system according to variation of some or all of control actions V1-V6 about the values predetermined from calculation and/or prior experience for a successfully tuned accelerator.
- control actions V1-V6 shall be referred to as "injection phase control actions.”
- Some or all of the values V1-V6 may be varied about their preset values in sequence until each produces the best (or a satisfactory) beam intensity for the first turn (or first few turns) of the accelerator and the proper location in space for that first orbit.
- the sequence of variation may be altered in a random fashion to establish the best operation and to avoid the possibility of a local maximum that is not the best possible.
- V1-V6 may be varied in this stage of operation as well. If the process cannot terminate successfully, the system may produce an alarm (not shown) and/or a history log (not shown) of the changes V(i) and results D(j).
- one purpose of having a specialized Feedback Loop I 524 for the first turn or few turns is to ensure that the injected beam misses the injection apparatus, which may be an injection gun.
- the beam gains energy at each turn. As the energy increases with each turn the orbits expand in average radial location. Until this expansion is sufficient to have all successive orbits avoid the injector, the system may rely on betatron oscillations of the beam (in vertical and radial position) to ensure the beam missing the injection apparatus. This may require an adjustment of injection apparatus position, injection direction, injection energy, beam intensity and guide field values as is carried out in V1-V6.
- Feedback Loop II 526 processes the beam from the end of Loop I through the full energy first beam use.
- Some possible adjustments such as core and magnet temperature (V7 and V8) monitor possible system changes and adjust coolant flow appropriately.
- Other adjustments deal with beam position and energy at different positions and vary the guide fields at different locations to avoid losing the beam.
- One possibility that could cause the beam to be lost is an unstable tune of the guide magnetic fields as a function of position. Resonances may be encountered that deflect the beam into the walls of the vacuum chamber at some radius. These resonances may also cause the beam profile to expand sufficiently so as to cause a loss of intensity at extraction or use with an internal target or at some intermediate energy less than that of use without losing the entire beam.
- the diagnostic measurements D(j) may detect beam losses and beam position and the adjustments V1-V12 treat each of these possibilities and mitigate beam losses.
- the beam is brought to final energy ready for use.
- the variations V1-V12 may be carried out automatically according to a predetermined algorithm, or may be performed partially or even completely manually. It will be understood that other parameters than V1-V12 may be varied in this stage of operation as well. If Feedback Loop II 526 is not successful according to predetermined conditions an alarm may be established with a history of all adjustments and diagnostic readings.
- the beam may be a short pulse only encompassing a spatial extent less than one turn or it may encompass a few turns.
- the beam may be expanded in duty cycle so that the full range of energies is encompassed in the vacuum chamber and every turn is occupied with beam. This will change the effects of space charge interactions and ion production.
- the management of the beam to the full energy for extraction or internal use may include this part of the automated adjustments.
- Feedback Loop III 528 begins at the full energy beam condition and optimizes the extraction of the beam or use of the beam with an internal target.
- Dl - DIl are made.
- use phase diagnostic measurements it is determined if the extracted or internally used beam properties are optimized to predetermined requirements.
- control actions V1-V12 may be referred to as "use phase control actions."
- Feedback Loop III 528 processes the beam from the full energy first beam extraction or internal use through the optimization of the extracted or internally used beam. This feedback loop includes obtaining the appropriate beam intensity and beam profile in space and energy. This tune may be accomplished using a short beam and finally may use the high duty cycle operation wherein the beam fills the entire vacuum chamber occupying all turns and all energies from injection to use.
- V1-V12 may be carried out automatically according to a predetermined algorithm, or may be performed partially or even completely manually. It will be understood that other parameters than V1-V12 may be varied in this stage of operation as well. As with the earlier feedback loops a failure to meet preset standards may produce an alarm with a history of all diagnostic readings and adjustments.
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US2464008P | 2008-01-30 | 2008-01-30 | |
US12/351,241 US8280684B2 (en) | 2008-01-09 | 2009-01-09 | Diagnostic methods and apparatus for an accelerator using induction to generate an electric field with a localized curl |
US12/351,234 US8264173B2 (en) | 2008-01-09 | 2009-01-09 | Methods and systems for accelerating particles using induction to generate an electric field with a localized curl |
PCT/US2009/032651 WO2009097536A1 (en) | 2008-01-30 | 2009-01-30 | Methods for diagnosing and automatically controlling the operation of a particle accelerator |
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US10340051B2 (en) * | 2016-02-16 | 2019-07-02 | General Electric Company | Radioisotope production system and method for controlling the same |
US10123406B1 (en) | 2017-06-07 | 2018-11-06 | General Electric Company | Cyclotron and method for controlling the same |
CN108318909A (en) * | 2018-02-08 | 2018-07-24 | 中国科学院近代物理研究所 | A kind of beam for ion accelerator damages detector assembly |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3348089A (en) * | 1963-07-29 | 1967-10-17 | Ibm | Cyclotron accelerator having the electrostatic field appearing across a nonlinear gap |
US3742212A (en) * | 1971-02-16 | 1973-06-26 | Univ Leland Stanford Junior | Method and apparatus for pulsed ion cyclotron resonance spectroscopy |
US4381450A (en) * | 1981-01-22 | 1983-04-26 | The United States Of America As Represented By The Secretary Of The Air Force | Pulsed radiation dosimetry apparatus |
JPH05198398A (en) * | 1991-03-19 | 1993-08-06 | Hitachi Ltd | Circular accelerator and beam incidence method for circular accelerator |
JP3121017B2 (en) * | 1993-09-20 | 2000-12-25 | 株式会社日立製作所 | Beam adjustment method |
JP3307059B2 (en) * | 1994-03-17 | 2002-07-24 | 株式会社日立製作所 | Accelerator, medical device and emission method |
WO1998057335A1 (en) * | 1997-06-10 | 1998-12-17 | Adelphi Technology, Inc. | Thin radiators in a recycled electron beam |
JP3602985B2 (en) * | 1999-07-29 | 2004-12-15 | 株式会社日立製作所 | Method and apparatus for controlling circular accelerator |
JP2003522398A (en) * | 2000-02-11 | 2003-07-22 | バリアン・セミコンダクター・エクイップメント・アソシエイツ・インコーポレイテッド | Method and apparatus for operating a high energy accelerator in a low energy mode |
JP3736343B2 (en) * | 2000-03-09 | 2006-01-18 | 三菱電機株式会社 | DC electron beam accelerator and DC electron beam acceleration method thereof |
JP4257741B2 (en) * | 2004-04-19 | 2009-04-22 | 三菱電機株式会社 | Charged particle beam accelerator, particle beam irradiation medical system using charged particle beam accelerator, and method of operating particle beam irradiation medical system |
CN100420353C (en) * | 2004-04-19 | 2008-09-17 | 三菱电机株式会社 | Charged-particle beam accelerator, particle beam radiation therapy system, and method of operating the particle beam radiation therapy system |
US7415095B2 (en) * | 2004-10-01 | 2008-08-19 | Siemens Aktiengesellschaft | System and method utilizing adaptive radiation therapy framework |
-
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Non-Patent Citations (7)
Title |
---|
FARIAS R H A ET AL: "Optical beam diagnostics for the LNLS synchrotron light source", PROCEEDINGS OF THE 1997 PARTICLE ACCELERATOR CONFERENCE : VANCOUVER, B.C., CANADA, 12 - 16 MAY 1997, IEEE, PISCATAWAY, NJ, USA, vol. 2, 12 May 1997 (1997-05-12), pages 2238-2240, XP010323345, DOI: 10.1109/PAC.1997.751168 ISBN: 978-0-7803-4376-4 * |
FARIAS R H A ET AL: "Orbit measurement and correction in the LNLS Synchrotron Light Source", PROCEEDINGS OF THE 1997 PARTICLE ACCELERATOR CONFERENCE : VANCOUVER, B.C., CANADA, 12 - 16 MAY 1997, IEEE, PISCATAWAY, NJ, USA, vol. 2, 12 May 1997 (1997-05-12), pages 2096-2098, XP010323156, DOI: 10.1109/PAC.1997.751119 ISBN: 978-0-7803-4376-4 * |
FARIAS R H A ET AL: "Ramping efficiency studies in the LNLS synchrotron light source", PROCEEDINGS OF THE 1997 PARTICLE ACCELERATOR CONFERENCE : VANCOUVER, B.C., CANADA, 12 - 16 MAY 1997, IEEE, PISCATAWAY, NJ, USA, vol. 3, 12 May 1997 (1997-05-12), pages 3740-3742, XP010322574, DOI: 10.1109/PAC.1997.753403 ISBN: 978-0-7803-4376-4 * |
I Endo ET AL: "Coherent bremsstrahlung from the internal target of the 1.3 GeV electron synchrotron", Nuclear Inst. and Methods in Physics Research, A, 1 January 1986 (1986-01-01), pages 493-497, XP055124796, DOI: 10.1016/0168-9002(86)90643-1 Retrieved from the Internet: URL:http://www.sciencedirect.com/science/article/pii/0168900286906431 [retrieved on 2014-06-23] * |
RODRIGUES A R D ET AL: "Commissioning and operation of the Brazilian Synchrotron Light Source", PROCEEDINGS OF THE 1997 PARTICLE ACCELERATOR CONFERENCE : VANCOUVER, B.C., CANADA, 12 - 16 MAY 1997, IEEE, PISCATAWAY, NJ, USA, vol. 1, 12 May 1997 (1997-05-12), pages 811-813, XP010322788, DOI: 10.1109/PAC.1997.749845 ISBN: 978-0-7803-4376-4 * |
See also references of WO2009097536A1 * |
UENG T S ET AL: "Turn-by-turn beam position measurement for 1.3 GeV booster synchrotron", PROCEEDINGS OF THE 1995 PARTICLE ACCELERATOR CONFERENCE : PAPERS FROM THE SIXTEENTH BIENNIAL PARTICLE ACCELERATOR CONFERENCE, AN INTERNATIONAL FORUM ON ACCELERATOR SCIENCE AND TECHNOLOGY HELD MAY 1 - 5, 1995 IN DALLAS, TEXAS, IEEE, NEW YORK, US, vol. 4, 1 May 1995 (1995-05-01), pages 2524-2526, XP010166270, DOI: 10.1109/PAC.1995.505605 ISBN: 978-0-7803-2934-8 * |
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WO2009097536A1 (en) | 2009-08-06 |
CN101953237A (en) | 2011-01-19 |
EP2243340A4 (en) | 2014-08-20 |
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