CN110267426A - A kind of radio frequency four polar field accelerator and its accelerated method - Google Patents
A kind of radio frequency four polar field accelerator and its accelerated method Download PDFInfo
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- CN110267426A CN110267426A CN201910400892.7A CN201910400892A CN110267426A CN 110267426 A CN110267426 A CN 110267426A CN 201910400892 A CN201910400892 A CN 201910400892A CN 110267426 A CN110267426 A CN 110267426A
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Abstract
The present invention relates to a kind of radio frequency four polar field accelerator and its accelerated methods, the accelerator is divided into radial matching section, shaped segment, small energy acceptance section and accelerating sections according to the changing rule of basic parameter, small energy acceptance section is used to complete the pack to the line from shaped segment, in Bunching process, small energy acceptance is realized by configuring small modulation factor and being slowly increased it, and 2%~3% line is lost by small energy acceptance.The present invention is just lost when compared with low energy by deliberately losing sub-fraction line (efficiency of transmission is still higher than 95%) so that this part line can not obtain energy gain, to significantly reduce the damage for losing line to rfq accelerator electrode.Accelerating sections further comprises energization section and conventional accelerating sections in the present invention, and shaped segment is made to obtain smaller longitudinal emittance, and the high quality of beam line of " clean " is thus obtained in rfq accelerator exit.
Description
Technical field
The present invention relates to radio frequency four polar field accelerator dynamics Design technical fields more particularly to a kind of radio frequency four polar field to add
Fast device and its accelerated method.
Background technique
Radio frequency four polar field (RFQ) accelerator is a kind of low energy ion linear accelerator proposed late 1960s, is led to
It is usually used in the direct current beam for directly accelerating to be drawn by ion source.This accelerator can either accelerate particle, its own also has
It is standby simultaneously to the transverse focusing effect of ion beam and longitudinal bunching action, can efficiently by milliampere grade, even hundred milliamperes of grades it is strong
Beamlet of wandering about as a refugee accelerates to every hertz of several MeV.This accelerator has been widely used for accelerator system front end injector, ion note
Enter, the fields such as high current neutron source and Accelerator driven clean energy resource.High beam intensity and CW operational mode are RFQ development in recent years
Main way.To solve the problems, such as high beam intensity bring space charge effect, various dynamics are proposed in the world and are accelerated,
Wherein most representative is that classical four sections of opinions and samming accelerate.
With reference to Fig. 1, classical four sections of opinions are according to rfq accelerator basic parameter (aperture a, electrode modulation Coefficient m, phasesWith
Voltage across poles V) changing rule, rfq accelerator is divided into four parts: 101 ' of radial matching section, 102 ' of shaped segment, slow pack
Section 103 ' and 104 ' of accelerating sections.Wherein, the horn mouth that the shape of 101 ' of radial matching section is opened as one, for realizing low energy biography
The matching between focusing system changed over time in the line and rfq accelerator not changed over time in defeated line；Shaped segment
102 ' allow line to form vertical structure, and slow 103 ' of bunching section is by line in longitudinal compression at a series of beam group, 104 ' of accelerating sections
By beam acceleration to final target energy.Samming accelerates to consider the coupling of rfq accelerator and line, core concept
Be so that line starts in shaped segment end, until rfq accelerator end remains isotropism, laterally and longitudinally between do not have
There is the free energy for additionally serving as generating emittance exchange, to control the growth of emittance.
Rfq accelerator can be abstracted as the high-frequency electrical quadrupole lense system with acceleration function, using symmetrically placed along Z axis
Four high-frequency electric fields that there are the electrodes of periodically small modulation to generate focus and accelerated current.When four electrodes do not add modulation
When, loading cycle is the alternating voltage of T, by taking cation as an example, t moment, and added voltage such as Fig. 2 (a) on electric quadrupole lens,
The direction x is received blooming effect by focussing force, the direction y；And voltage such as Fig. 2 added on the t+T/2 moment, electric quadrupole lens
(b), by blooming effect, the direction y is so recycled by focussing force in the direction x, and cation all will be by x, y both direction
The focussing force of alternating gradient.
After four electrode surfaces of rfq accelerator added periodically small modulation, as shown in figure 3, longitudinal direction will be generated
Electric field component, halved tie stream are accelerated.The minimum-value aperture of electrode cartridge is a, and maximum diameter of hole is ma, and wherein m is the index of modulation, from
The distance of minimum-value aperture to maximum diameter of hole is an accelerator module length.Between two adjacent minimum-value apertures or between maximum diameter of hole
A distance referred to as modulation period, each modulation period include two accelerator modules, and synchronization adjacent two units
Longitudinal electric field is contrary.When in t moment, some accelerator module is accelerated for beam group, since beam is rolled into a ball in accelerator module
Traveling time and high-frequency electric field phase change time are all T/2, and beam is rolled into a ball after carrying out next accelerator module, decelerating field originally
Reversely, so beam group remains to obtain lasting acceleration.
Existing RFQ dynamics Design scheme is intended to realize maximum efficiency of transmission and quality of beam as well as possible, and
By horizontal, vertical r. m.s. emittance as the judgment criteria of quality of beam quality.Gao Liuqiang, high power and high stability straight line
The development of accelerator, to the control of beam loss, more stringent requirements are proposed, that is, proposes to quality of beam tightened up
It is required that.In addition to line r. m.s. emittance, the emittance comprising more high proportion particle, such as the transmitting comprising 99.9% particle
Degree, becomes the new standard of rfq accelerator quality of beam quality.
It found, although existing rfq accelerator efficiency of transmission can reach very high (being greater than 98%), added in RFQ in recent years
After the fast device operation several years, RFQ efficiency of transmission has to be declined to some extent, or even starts the phenomenon that fluctuation of service occur,
This possible one of reason is to exist to lose with the comparable particle of RFQ leaving energy in RFQ, and the loss of high energy particle can be to electricity
Pole generates biggish damage, the serious curtailment service life of rfq accelerator.In addition, existing rfq accelerator outlet line includes
The emittance of 99.9% particle is all bigger than normal, is unfavorable for transmitting in the acceleration of subsequent accelerating structure, particle is in subsequent accelerating structure
The probability of loss is higher.
Summary of the invention
Technical problem to be solved by the invention is to provide a kind of radio frequency four polar field accelerator of low electrode damage and its add
Fast method.Further the technical problem to be solved is that provide the radio frequency four of a kind of damage of low electrode, high quality of beam by the present invention
Pole accelerator and its accelerated method.
Inventor is the study found that in existing dynamics Design scheme, and in order to pursue maximum efficiency of transmission, RFQ accelerates
Line all is received using big acceptance in device overwhelming majority unit, it means that all particles can obtain energy gain.
Since the rfq accelerator of finite length determines incomplete insulation pack, the transmission of 100% line, therefore, RFQ cannot achieve
Always lose line in accelerator, and these by lost particle due to obtaining energy gain and energy is higher, can be to rfq accelerator
Electrode is generated compared with macrolesion.
To solve above-mentioned high electrode damage problem, a kind of radio frequency four polar field accelerator of the present invention, according to basic ginseng
Several changing rules is divided into radial matching section, shaped segment, small energy acceptance section and accelerating sections；The radial matching section is used for
Realize the focusing system changed over time in the input line and radio frequency four polar field not changed over time in transfers line
Between matching；The shaped segment is used to that the line from the radial matching section to be made to form vertical structure；The small energy connects
It is used to complete the pack to the line from the shaped segment by degree section, in Bunching process, by configuring small modulation factor
And be slowly increased it and realize small energy acceptance, 2%~3% line and guarantee are lost by small energy acceptance
Efficiency of transmission is higher than 95%；The accelerating sections for will the beam acceleration from the small energy acceptance section to final goal energy
Amount.
In above-mentioned accelerator, it is preferred that the accelerating sections includes energization section and conventional accelerating sections, and the energization section is used for
Energy by the line for quickling increase modulation factor come fast lifting from the small energy acceptance section；The routine adds
Fast section for will the beam acceleration from the energization section to the final goal energy.
In above-mentioned accelerator, it is preferred that the shaped segment is by increasing accelerator module quantity and optimization modulation factor
And locking phase, obtain the smaller longitudinal emittance of compared with the prior art conventional shaped segment.
In above-mentioned accelerator, it is preferred that in the shaped segment, accelerator module quantity is 80-90, modulation factor by
1 is gradually increased between 1.05~1.07, and locking phase is gradually increased between -80 °~-75 ° by -90 °.
In above-mentioned accelerator, it is preferred that the radial matching section is by increasing accelerator module quantity and optimizing its electrode
Shape, make match beam parameters in alpha reduce and beta increase, with reduce transfers line transmission when line envelope or
Person places beam diagnostics component space before increasing rfq accelerator.
In above-mentioned accelerator, it is preferred that in the radial matching section, accelerator module quantity is 10~30, described
The alpha in beam parameters is matched between 0.5~1, beta is between 3~8cm/rad.
In above-mentioned accelerator, it is preferred that the setting range of its lateral aggregation intensity is 4~8, according to operation duty ratio,
The setting range of sparking coefficient is 1.2~2.5.
Correspondingly, the present invention also provides a kind of accelerated method of radio frequency four polar field accelerator, which accelerates
Device is divided into radial matching section, shaped segment, small energy acceptance section and accelerating sections according to the changing rule of basic parameter, described to add
Fast method includes: that the radial matching section realizes the input line not changed over time in transfers line and radio frequency quadrupole
The matching between focusing system changed over time in；It is vertical that the shaped segment forms the line from the radial matching section
To structure；The small energy acceptance section completes the pack to the line from the shaped segment, in Bunching process, by matching
It sets small modulation factor and is slowly increased it and realize small energy acceptance, lose 2% by small energy acceptance~
3% line simultaneously guarantees that efficiency of transmission is higher than 95%；The accelerating sections is by the beam acceleration from the small energy acceptance section
To final goal energy.
In above-mentioned accelerated method, it is preferred that the accelerating sections includes energization section and conventional accelerating sections, and the accelerating sections will
Beam acceleration to final goal energy from the small energy acceptance section includes: the energization section by keeping modulation factor fast
Speed increases the energy for carrying out line of the fast lifting from the small energy acceptance section；The routine accelerating sections will come from the increasing
Can section beam acceleration to the final goal energy.
Compared with the prior art, the present invention has the following advantages:
1, low electrode damage: the present invention in, rfq accelerator include radial matching section, shaped segment, small energy acceptance section and
Accelerating sections breaks through the constraint of Traditional Thinking in design, does not pursue maximum efficiency of transmission, but in small energy acceptance section
2%~3% line is deliberately lost by small energy acceptance, so that this part line can not obtain energy gain,
It is just lost when compared with low energy, and line Energy Loss spectrum is discrete spectrum, energy is from 35keV to 300keV, to significantly drop
Damage of the low loss line to rfq accelerator electrode.Wherein, rfq accelerator efficiency of transmission of the present invention, compared to existing power
Design method is learned, can additionally reduce by 2%~3% or so, but be still higher than 95%.
2, in the present invention, accelerating sections further comprises energization section and conventional accelerating sections, and energization section comes from for fast lifting
The energy of the line of small energy acceptance section compares entire accelerating sections and all uses conventional accelerating sections technology in the prior art, energization section
Setting can shorten the length of accelerating sections of the present invention.From the perspective of from another angle, since small energy acceptance section modulation factor is smaller
And increasing slowly, the setting of energization section is to compensate for small energy acceptance section bring length and increases, so that small energy acceptance
The length for spending section and energization section is suitable with the length of slow bunching section in the prior art, i.e., the present invention is not increasing or do not increasing significantly
Low electrode damage is realized in the case where lengthening degree.
3, it high quality of beam: in the present invention, further, is adjusted by the accelerator module quantity and optimization that increase shaped segment
The factor and locking phase processed obtain smaller longitudinal emittance.Shaped segment+small energy acceptance with smaller longitudinal emittance
Section+energization section makes rfq accelerator exit obtain the high-current beam of " clean ", i.e., r. m.s. emittance and includes more high proportion beam
The emittance of stream is all smaller, and emittance of the line comprising 99.9% particle and the acceptance ratio of subsequent accelerating structure are smaller (small
In 1/5), it is small that line loses probability in subsequent accelerating structure, meets subsequent Gao Liuqiang, high power and high stability linear accelerating
The requirement of device.
4, the twiss parameter of traditional rfq accelerator matching line is big alpha and small beta, such matching way meeting
Requirements at the higher level, the design of unfavorable transfers line are proposed to the line that transfers line comes.In the present invention, radial matching section into
For one step using more accelerator modules and its electrode shape is optimized, the twiss parameter for obtaining matching line is small alpha and big
Beta places beam diagnostics element sky before the envelope or increase rfq accelerator of line in the transmission of transfers line to reduce
Between.
Detailed description of the invention
Specific embodiments of the present invention will be described in further detail with reference to the accompanying drawing.
Fig. 1 is the schematic diagram of each boost phase in traditional rfq accelerator.
Fig. 2 is voltage shape of the electric quadrupole lens in t moment (a) and t+T/2 moment (b).
Fig. 3 is rfq accelerator acceleration function schematic diagram.
Fig. 4 is a kind of schematic diagram of each boost phase in rfq accelerator of the present invention.
Fig. 5 is another schematic diagram of each boost phase in rfq accelerator of the present invention.
Fig. 6 is the inlet electrode shape comparison diagram of rfq accelerator of the present invention and traditional rfq accelerator.
Fig. 7 is the modulation factor comparison diagram of rfq accelerator of the present invention and traditional rfq accelerator.
Fig. 8 is the locking phase comparison diagram of rfq accelerator of the present invention and traditional rfq accelerator.
Fig. 9 is the beam phase space and longitudinal acceptance of rfq accelerator of the present invention and traditional rfq accelerator in Unit 150
The comparison diagram of situation.
Figure 10 is the loss of power comparison diagram of rfq accelerator of the present invention and traditional rfq accelerator.
Figure 11 is the outlet quality of beam comparison diagram of rfq accelerator of the present invention and traditional rfq accelerator.
Specific embodiment
With reference to Fig. 4, according to the changing rule of rfq accelerator basic parameter, rfq accelerator of the present invention is divided into radial matching
Section 101, shaped segment 102, small energy acceptance section 103 and accelerating sections 104.
Radial matching section 101 is for realizing the input line and radio frequency quadrupole not changed over time in transfers line
The matching between focusing system changed over time in.
Shaped segment 102 is used to that the line from radial matching section 101 to be made to form vertical structure.
Small energy acceptance section 103 is used to complete the pack to the line from shaped segment 102, in Bunching process, leads to
It crosses and configures small modulation factor and realize small energy acceptance, 2%~3% line is lost by small energy acceptance simultaneously
Guarantee that efficiency of transmission is higher than 95%.Receive section in entire small energy, modulation factor is slowly increased, and locking phase increase is relatively
Fastly.
Accelerating sections 104 in the future from childhood the beam acceleration of energy acceptance section 103 to final goal energy.
It is understood that rfq accelerator is according to modulation lines and physics law, artificial is divided into several parts, in fact
For an entirety；Moreover, in practical applications, the modulation factor of rfq accelerator any position, locking phase, aperture all may be used
It is obtained with being directly arranged by the terminal of existing program.
With reference to Fig. 5, accelerating sections 104 further includes energization section 1041 and conventional accelerating sections 1042, i.e., RFQ of the present invention adds
Fast device is divided into radial matching section 101, shaped segment 102, small energy acceptance section 103, energization section 1041 and conventional accelerating sections
1042 5 parts.
Wherein, energization section 1041 is used for by quickling increase modulation factor come fast lifting come energy acceptance section from childhood
The energy of 103 line, conventional accelerating sections 1042 for will the beam acceleration from energization section 1041 to final goal energy.
For radial matching section, the radial compatible portion of traditional rfq accelerator design only has 4-6 unit, about several cm
It is long, length ZrInterior, aperture gradually decreases to mean radius R0, laterally aggregation increases to B from 0max, the B (z) at any point=
(Bmax)/Zr* z can be directly inputted by the terminal of existing program, work as ZrWhen only several cm, such matching way can be right
The line that transfers line comes proposes requirements at the higher level.The twiss parameter of traditional rfq accelerator matching line be big alpha and
Small beta, the design of this unfavorable transfers line.
In the present invention, radial matching section 101 is using more units and optimizes its electrode shape, that is, reaches identical
BmaxZrIncrease, such as 10-30 unit, makes to match alpha reduction and beta in beam parameters and increase, obtain matching line
Twiss parameter is small alpha and big beta, alpha between 0.5~1, and beta is between 3~8cm/rad.The matching of optimization
Beam parameters can reduce the envelope of the line in the transmission of transfers line, and small line envelope can reduce line sense in low energy
The nonlinear effect received, improves the quality of beam of RFQ entrance, or places beam diagnostics element before capable of increasing rfq accelerator
Space.
For shaped segment, play a crucial role to the formation of rfq accelerator longitudinal direction emittance.Compared with the prior art in it is conventional at
Shape section, shaped segment 102 of the present invention complete the forming of line using more units, while optimizing modulation factor and locking phase,
Obtain the smaller longitudinal emittance of compared with the prior art conventional shaped segment.Specifically, in shaped segment 102, accelerator module quantity
Between 80-90, modulation factor is gradually increased between 1.05~1.07 by 1, and locking phase is gradually increased to -80 ° by -90 °
Between~-75 °, longitudinal r. m.s. emittance is between 0.15~0.25mm.mrad.
So far, shaped segment has smaller longitudinal emittance, adds small energy acceptance section+energization section, small energy connects
Configure by degree section prevent 2~3% line is from obtaining energy gain, RFQ unit transverse is equivalent to quadrupole iron, energy with together
The biggish particle of capacity volume variance is walked, is transmitted in quadrupole iron, due to mismatch, which can be lost in RFQ, so that
Rfq accelerator exit obtains the high-current beam of " clean ", and the emittance comprising 99.9% particle is less than downstream accelerator structure and connects
1/5 spent.
In actual rfq accelerator design process, usually also need to carry out following preparation.
(1) according to the frequency of rfq accelerator, conventional accelerating sections entrance energy, the maximum modulation factor, losing equation according to horse has
Solution, explores the stability region of minimum-value aperture.
Before design rfq accelerator design, some parameters, such as frequency, particle kind, Bunch current export line
Energy can be all distinctly claimed.
(2) in aforementioned stable region, under the premise of taking into account transverse focusing and longitudinal acceleration, suitable RFQ is selected to add
Fast device minimum-value aperture and modulation factor.
When selecting minimum-value aperture and modulation factor, usually accelerator coefficient is made to always slightly greater than focusing factor.
(3) according to transverse focusing intensity, sparking coefficient and operational mode, the voltage across poles of rfq accelerator is selected.
Wherein, the setting range of lateral aggregation intensity is 4~8, guarantees the lateral confinement to line, according to operation duty
Than the setting range for coefficient of striking sparks is 1.2~2.5, reduces the difficulty that high frequency is taken exercise.
(4) parameter selected and determined based on above-mentioned steps (1)~(3) will according to rfq accelerator related physical rule
It is sequentially divided into radial matching section 101, shaped segment 102, small energy acceptance section 103 and accelerating sections 104；Accelerating sections 104 into
One step includes energization section 1041 and conventional accelerating sections 1042.
Based on radio frequency four polar field accelerator disclosed in above content, the present invention accordingly provides a kind of radio frequency four polar field accelerator
Accelerated method, which is divided into radial matching section 101, shaped segment according to the changing rule of basic parameter
102, small energy acceptance section 103 and accelerating sections 104, accelerated method include:
(1) radial matching section 101 realizes the input line not changed over time in transfers line and radio frequency quadrupole
The matching between focusing system changed over time in.
(2) shaped segment 102 makes the line from radial matching section 101 form vertical structure.
(3) the small completion of energy acceptance section 103 passes through the pack of the line from shaped segment 102 in Bunching process
It configures small modulation factor and is slowly increased it and realize small energy acceptance, lose 2% by small energy acceptance
~3% line simultaneously guarantees that efficiency of transmission is higher than 95%.
(4) accelerating sections 104 in the future from childhood the beam acceleration of energy acceptance section 103 to final goal energy.
Further, accelerating sections 104 includes energization section 1041 and conventional accelerating sections 1042, and step (4) includes:
(41) energization section 1041 is by quickling increase modulation factor come fast lifting come energy acceptance section 103 from childhood
The energy of line.
(42) it is conventional accelerate 1042 sections by the beam acceleration from energization section 1041 to final goal energy.
The comparative experiments of rfq accelerator of the present invention and traditional rfq accelerator
One, traditional rfq accelerator
With reference to Fig. 1, traditional rfq accelerator is divided into 101 ' of radial matching section, 102 ' of shaped segment, 103 ' of slow bunching section and acceleration
Tetra- parts 104 ' of section.The proton beam of 15mA is accelerated into 2.1MeV to 35keV.
101 ' of radial matching section uses 5 units.
102 ' of shaped segment uses Unit 77, and modulation factor m progressively increases to 1.14 by 1, and locking phase is by -90 ° of entrance
- 78.4 ° are gradually increased to, continuous beam forms beam after by shaped segment and rolls into a ball and accelerated on a small quantity.
Slow 103 ' of bunching section uses Unit 166, and modulation factor m increases to 2.3 by 1.14, and locking phase is increased by 78.4 °
To -26 °.
In 104 ' of accelerating sections, modulation factor m almost keeps 2.3 constant, and locking phase is slowly increased to -23 ° by -26 °, will
Particle accelerates to final goal energy emanated energy 2.1MeV.
Two, rfq accelerator of the present invention
With reference to Fig. 4 and Fig. 5, rfq accelerator of the present invention is divided into radial matching section 101, shaped segment 102, small energy acceptance
Section 103 and accelerating sections 104；Wherein, accelerating sections 104 further comprises energization section 1041 and conventional accelerating sections 1042.
Accelerator frequency f is 162.5MHz, and minimum-value aperture a is 3.2mm, and the maximum modulation factor is 2.4；Operate in CW wave mould
Under formula, accelerate 15mA proton beam, voltage across poles chooses 65kV, sparking coefficient selection 1.2.
Radial matching section 101 uses Unit 27, and about 22cm, the twiss parameter for obtaining matching line is alpha 0.75
With beta 6.95cm/rad.
Shaped segment 102 uses Unit about 87, and the modulation factor of outlet is 1.067, and locking phase is -78 °, both less than traditional
Rfq accelerator.
It is 1.21 that small energy acceptance section 103, which exports modulation factor, and locking phase is -40 °；It is additional to lose 2%.
1041 major function of energization section is the energy of fast lifting line, and modulation factor quickly changes to 2.3 from 1.21,
Locking phase slowly changes to -23 ° from -40 °, this segment unit is about 56 element lengths.
In conventional accelerating sections 1042, modulation factor m almost keeps 2.3 constant, and locking phase is slowly increased to by -23 ° -
22.5 °, particle is accelerated into emanated energy 2.1MeV.
Three, the comparative analysis of the two
1, the comparison of inlet electrode shape
Referring to Fig. 6.In radial matching section 101 of the present invention, new matching beam parameters make line in transfers line
Line envelope when transmission reduces about 30% or places beam diagnostics component space about 100mm before increasing RFQ.
2, the comparison of each stage modulation factor, locking phase
Referring to figs. 7 and 8.In shaped segment 102 of the present invention, the modulation factor and locking phase of optimization form smaller longitudinal direction
Emittance, compared to traditional rfq accelerator, longitudinal emittance of shaped segment outlet reduces about 6%.
3, in the comparison of the beam phase space of Unit 150 and longitudinal acceptance
Referring to Fig. 9, the left side is tradition, and the right is the present invention.The energy acceptance of traditional RFQ almost receives all beams
Stream, efficiency of transmission are up to 99.6%.And rfq accelerator of the present invention, intentional receiving portion line, efficiency of transmission about 97.2%,
Compared to existing dynamic design method, (in above-mentioned comparative experiments) can additionally reduce by 2% or so, but be still higher than 95%；
Not received small scale line will not obtain excessively high energy gain, occur in the focusing structure of rfq accelerator long-channel
It loses.
4, the comparison of loss of power situation
Referring to Figure 10.The proton beam of 15mA is accelerated to 2.1MeV, efficiency of transmission to 35keV by traditional rfq accelerator
Up to 99.6%, by the Energy distribution for 0.4% line that particles track obtains losing in rfq accelerator, be from 35keV to
The continuum of 2.1MeV, it means that there are the particle of higher-energy (quantity is also more) bombardments, in RFQ electrode surface, to cause
The injury of RFQ electrode influences the operation stability and service life of rfq accelerator.
Rfq accelerator efficiency of transmission of the present invention be 97.2%, line Energy Loss spectrum be discrete spectrum, Energy Loss range from
35keV to 300keV, 300keV are far smaller than the highest energy 2.1MeV that traditional rfq accelerator loses line, this will significantly be dropped
Low line loses the damage to rfq accelerator electrode.
5, the comparison of quality of beam is exported
Referring to Figure 11, the left side is tradition, and the right is the present invention.Traditional rfq accelerator length is about 4.2m, should undertake and add
Fast task undertakes constrain task to the transverse and longitudinal of line again, and when efficiency of transmission reaches 99.6%, the root mean square of line is sent out
Degree of penetrating available preferable control in rfq accelerator, hardly increases, but includes the emittance of 99.9% particle, especially
99.9% longitudinal emittance reaches 8.15mm.mrad in rfq accelerator outlet, and longitudinal r. m.s. emittance is 0.3mm.mrad.
In order to guarantee accelerator efficiency, subsequent high power linear accelerator usually has lesser longitudinal acceptance, even if using advanced
Superconductor technology, also difficulty does that big (usual subsequent structural uses superconducting proton linac, and longitudinal acceptance is about to longitudinal acceptance
For 27mm.mrad).
It has been generally acknowledged that the acceptance ratio of emittance of the line comprising 99.9% particle and subsequent accelerating structure is less than 1/5
When, the probability that line is lost in subsequent accelerator structure is smaller.And in traditional rfq accelerator, the ratio of the two is about 1/
3.3, it is big that line loses probability in subsequent accelerating structure, is unsatisfactory for subsequent Gao Liuqiang, high power and high stability linear accelerating
The requirement of device.
It is 0.25mm.mrad, the transmitting comprising 99.9% particle that rfq accelerator of the present invention, which exports longitudinal r. m.s. emittance,
Degree is 4.98mm.mrad, is less than traditional rfq accelerator and exports longitudinal emittance.Line include 99.9% particle emittance with
Acceptance (27mm.mrad) ratio of subsequent accelerating structure is about 1/5.4, and line loss probability is small, meets subsequent Gao Liuqiang, height
The requirement of power and high stability linear accelerator.
Technical solution provided by the present invention is described in detail above.Specific case used herein is to this hair
Bright principle and embodiment is expounded, method of the invention that the above embodiments are only used to help understand and its
Core concept.It should be pointed out that for those skilled in the art, in the premise for not departing from the principle of the invention
Under, it can be with several improvements and modifications are made to the present invention, these improvement and modification also fall into the protection of the claims in the present invention
In range.
Claims (9)
1. a kind of radio frequency four polar field accelerator, which is characterized in that the accelerator is divided into diameter according to the changing rule of basic parameter
To matching section, shaped segment, small energy acceptance section and accelerating sections；
The radial matching section is for realizing the input line and radio frequency four polar field not changed over time in transfers line
In matching between the focusing system that changes over time；
The shaped segment is used to that the line from the radial matching section to be made to form vertical structure；
The pack that the small energy acceptance section is used to complete to the line from the shaped segment passes through in Bunching process
It configures small modulation factor and is slowly increased it and realize small energy acceptance, lose 2% by small energy acceptance
~3% line simultaneously guarantees that efficiency of transmission is higher than 95%；
The accelerating sections for will the beam acceleration from the small energy acceptance section to final goal energy.
2. radio frequency four polar field accelerator as described in claim 1, which is characterized in that the accelerating sections includes energization section and routine
Accelerating sections, the energization section are used for by quickling increase modulation factor come fast lifting from the small energy acceptance section
The energy of line；The routine accelerating sections for will the beam acceleration from the energization section to the final goal energy.
3. radio frequency four polar field accelerator as claimed in claim 1 or 2, which is characterized in that the shaped segment is accelerated by increasing
Element number and optimization modulation factor and locking phase obtain the smaller longitudinal transmitting of compared with the prior art conventional shaped segment
Degree.
4. radio frequency four polar field accelerator as claimed in claim 3, which is characterized in that in the shaped segment, accelerator module number
Amount is 80-90, and modulation factor is gradually increased between 1.05~1.07 by 1, and locking phase is gradually increased to -80 ° by -90 °
Between~-75 °.
5. radio frequency four polar field accelerator as claimed in claim 1 or 2, which is characterized in that the radial matching section passes through increase
Accelerator module quantity simultaneously optimizes its electrode shape, makes to match alpha reduction and beta in beam parameters and increases, to reduce in low energy
Beam diagnostics component space is placed before the envelope of line or increase rfq accelerator when transmission line.
6. radio frequency four polar field accelerator as claimed in claim 5, which is characterized in that in the radial matching section, accelerate single
First quantity is 10~30, and the alpha in the matching beam parameters is between 0.5~1, and beta is between 3~8cm/rad.
7. radio frequency four polar field accelerator as described in claim 1, which is characterized in that the setting range of its lateral aggregation intensity is
4~8, according to operation duty ratio, the setting range for coefficient of striking sparks is 1.2~2.5.
8. a kind of accelerated method of radio frequency four polar field accelerator, which is characterized in that the radio frequency four polar field accelerator is according to basic ginseng
Several changing rules is divided into radial matching section, shaped segment, small energy acceptance section and accelerating sections, the accelerated method
The radial matching section realize in the input line and radio frequency four polar field not changed over time in transfers line with
Matching between the focusing system of time change；
The shaped segment makes the line from the radial matching section form vertical structure；
The small energy acceptance section completion passes through and configures in Bunching process to the pack of the line from the shaped segment
Small modulation factor simultaneously makes it be slowly increased the small energy acceptance of realization, loses 2%~3% by small energy acceptance
Line and guarantee efficiency of transmission be higher than 95%；
The accelerating sections is by the beam acceleration from the small energy acceptance section to final goal energy.
9. accelerated method as claimed in claim 8, which is characterized in that the accelerating sections includes energization section and conventional accelerating sections,
Beam acceleration to final goal energy from the small energy acceptance section includes: by the accelerating sections
The energization section passes through the line that quicklys increase modulation factor come fast lifting from the small energy acceptance section
Energy；
The routine accelerating sections is by the beam acceleration from the energization section to the final goal energy.
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| CN117395851A (en) * | 2023-10-09 | 2024-01-12 | 中国科学院近代物理研究所 | Compact ion implanter and ion implantation method for tumor treatment |
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