CN108834301B

CN108834301B - Electric contact method and structure of rotating capacitor rotor in synchrocyclotron

Info

Publication number: CN108834301B
Application number: CN201810682303.4A
Authority: CN
Inventors: 李鹏展; 张天爵; 尹蒙; 纪彬; 邢建升
Original assignee: China Institute of Atomic of Energy
Current assignee: China Institute of Atomic of Energy
Priority date: 2018-06-27
Filing date: 2018-06-27
Publication date: 2020-03-24
Anticipated expiration: 2038-06-27
Also published as: CN108834301A

Abstract

The invention discloses an electric contact structure of a rotating capacitor rotor in a synchrocyclotron, which has the technical scheme that the electric contact structure comprises a capacitor vacuum chamber, a capacitor rotor and a rotating shaft, wherein the capacitor rotor is rotatably arranged in the capacitor vacuum chamber, the rotating shaft is fixedly connected to one end of the capacitor rotor and is used for driving the capacitor rotor to rotate, the capacitor rotor comprises a disk part arranged in the middle and blade parts distributed along the circumferential outer side of the disk part, an electric connection rotating disk is arranged on the rotating shaft and is separated from the disk part, and an electric connection copper net is pressed between the disk part and the electric connection rotating disk; the invention has the effect of stably realizing electric contact under the condition of high-speed rotation.

Description

Electric contact method and structure of rotating capacitor rotor in synchrocyclotron

Technical Field

The invention relates to the field of synchrocyclotron, in particular to an electric contact structure of a rotating capacitor rotor in a synchrocyclotron.

Background

In order to adapt to the influence of relativity, the cavity frequency of the synchrocyclotron is gradually reduced in the ion acceleration process. After the beam is led out, the frequency of the cavity is quickly adjusted back to the initial acceleration frequency, and the acceleration of the next beam group is continued. The variation of the cavity frequency of the synchrocyclotron is generally achieved by a periodic rotating capacitor. In the design of the normal-temperature synchrocyclotron, the rotating speed of a rotating capacitor is very low, the structural design of a cavity can be complex, and the electrical contact structure among all the parts is complex. Conventional synchrocyclotron rotating capacitor rotor electrical contact methods exhibit significant limitations in the design of high speed rotating capacitors.

Disclosure of Invention

In view of the defects of the prior art, a first object of the present invention is to provide an electrical contact structure for a rotating capacitor rotor in a synchrocyclotron, which has an advantage in that electrical contact can be stably achieved under a high-speed rotation condition.

In order to achieve the purpose, the invention provides the following technical scheme: a method for electrically contacting a rotating capacitor rotor in a synchrocyclotron electrically contacts a rotating shaft with the capacitor rotor; the rotating shaft is provided with an electric connection turntable; a plane narrow gap with a gap smaller than 0.2mm with the electric connection turntable is arranged in the capacitance vacuum chamber to form a grounding capacitor.

By adopting the technical scheme, the rotating shaft is electrically contacted with the capacitor rotor, so that the rotating shaft and the capacitor rotor are at the same potential; and due to the narrow plane gap, the electric turntable and the side wall of the capacitance vacuum chamber form a grounding capacitor. As known in the prior art, the resistance value of the capacitor is close to zero in the high-frequency field, so that the resistance value is equal to that of the electric turntable and the capacitor vacuum chamber cavity shell which are both at the ground potential. Compared with the mode that the electric brush is arranged on the rotating shaft of the rotating capacitor and is grounded with the housing of the cavity. Because the electric turntable is not in direct contact with the cavity shell, the problems of abrasion and temperature rise are avoided, and stable grounding can be still kept after long-time use.

A second object of the present invention is to provide an electrical contact structure of a rotating capacitor rotor in a synchrocyclotron, which has an advantage in that electrical contact can be stably achieved under a high-speed rotation condition.

In order to achieve the purpose, the invention provides the following technical scheme: an electric contact structure of a rotating capacitor rotor in a synchrocyclotron comprises a capacitor vacuum chamber, the capacitor rotor and a rotating shaft, wherein the capacitor rotor is rotatably arranged in the capacitor vacuum chamber, the rotating shaft is fixedly connected to one end of the capacitor rotor and is used for driving the capacitor rotor to rotate, the capacitor rotor comprises a disk part arranged in the middle and blade parts distributed along the circumferential outer side of the disk part, an electric connection rotating disk which is spaced from the disk part is arranged on the rotating shaft, and an electric connection copper net is pressed between the disk part and the electric connection rotating disk; and a plane narrow gap for high-frequency grounding is arranged between one side of the power connection turntable, which is far away from the disk part, and the side wall of the capacitance vacuum chamber.

By adopting the technical scheme, the electric connection effect of the surface contact is much better than that of the point contact in the high-frequency field. The power connection copper net is arranged between the disc part and the power connection turntable under the pressure, so that stable surface contact conduction of the disc part and the power connection turntable is realized; and the electrified copper mesh has good conductive performance, and the contact resistance is reduced. In addition, because the power connection turntable and the side wall of the capacitance vacuum chamber have a plane narrow gap, and electrons of the disk part can move to the power connection turntable through the power connection copper net, a grounded capacitor is formed between the power connection turntable and the side wall of the capacitance vacuum chamber. And because the grounding capacitor belongs to the high-frequency field, the resistance value of the capacitor is very low in the high-frequency field, thereby realizing high-frequency grounding. The grounding mode has no problems of abrasion and temperature rise because the electric turntable is not in direct contact with the cavity shell, and can still keep stable grounding after long-time use.

The invention is further configured to: the disc part is provided with an annular groove on one side facing the electric connection rotary disc, the electric connection copper net is annular, one end of the electric connection copper net is embedded into the annular groove, and the other end of the electric connection copper net is abutted to the electric connection rotary disc.

By adopting the technical scheme, the radial movement of the power connection copper net which can possibly occur under the high-speed rotation synchronous with the rotating shaft can be effectively limited by the mode of embedding the power connection copper net into the annular groove. The position stability of the power connection copper net under high-speed rotation is ensured.

The invention is further configured to: the power connection copper net has elasticity, and when the power connection copper net is not deformed, the excircle radius of the annular groove of the radius of the power connection copper net is equal to that of the annular groove of the radius of the power connection copper net.

By adopting the technical scheme, compared with an electric copper ring and the like, the electric copper network has certain deformability; and when the power connection copper net is not deformed, the excircle radius of the annular groove with the radius is increased, so that the friction between the power connection copper net and the annular groove is increased, and the position stability of the power connection copper net is further ensured.

The invention is further configured to: the power connection copper mesh is a beryllium copper mesh.

By adopting the technical scheme, the beryllium copper wire mesh has better conductivity in the copper wire mesh, so that the contact resistance can be effectively reduced.

The invention is further configured to: and one side of the capacitance vacuum chamber is fixedly connected with a magnetic fluid sealing piece for the penetration of the rotating shaft.

By adopting the technical scheme, the dynamic seal is required to be used in the design of the synchrocyclotron. The magnetic fluid seal belongs to one kind of rotary seal, and utilizes the fluidity and magnetic permeability of magnetic fluid materials to fill a seal gap under the action of a uniform magnetic field to form an O-shaped ring so as to realize vacuum seal. The magnetic fluid seal has the advantages of high rotating speed, no abrasion, high working reliability, lower water cooling requirement, good vacuum seal and the like. Meanwhile, the magnetofluid sealing element is rigidly connected with the rotor through the coupler, so that the phenomenon of losing rotation possibly occurring in permanent magnet transmission is avoided.

The invention is further configured to: the surface of the rotating shaft is sprayed with alumina ceramics.

By adopting the technical scheme, the surface of the alumina ceramic has the function of blocking, and the electric contact between the rotating shaft and the cavity shell of the vacuum chamber can be effectively avoided.

The invention is further configured to: the connecting circular hole is formed in the disc portion, a connecting boss which is tightly matched and connected in the connecting circular hole is arranged on the rotating shaft facing one end of the disc portion, and the axial length of the connecting boss is equal to that of the connecting circular hole.

By adopting the technical scheme, the concentric positioning between the rotating shaft and the disk part is realized through the connecting round hole and the connecting boss; simultaneously, the axial lengths of the connecting boss and the connecting circular hole are set to be equal, the connecting area between the connecting boss and the disc part is increased to the maximum extent, and the rotating shaft and the disc part are stably connected.

The invention is further configured to: the disk portion and the blade portion have the same thickness.

Through adopting above-mentioned technical scheme for disc portion and blade portion can use same piece copper to process, make processing technology convenient, and do not waste the copper material.

The invention is further configured to: the diameter of the connecting round hole is 9-10.5 mm.

By adopting the technical scheme, the size of the connecting round hole is selected to be matched with the size of the screw for fixing the capacitor rotor and the rotating shaft. If the size of the connecting circular hole is too small, the capacitor rotor and the rotating shaft are not fastened and contacted enough at the center; if too big, the machining deviation will enlarge, and the precision is difficult to control, may lead to the electric capacity rotor and the pivot decentraction to appear. A diameter of 9 to 10.5mm is therefore a measure which is compatible with a central position fastening and concentricity.

In summary, the invention has the following advantages:

1. the mode of forming the grounding capacitor is used for high-frequency grounding, so that the problems of abrasion and temperature rise are avoided, and the service life is prolonged;

2. the magnetic fluid is used for sealing, so that the magnetic fluid sealing device has the advantages of high rotating speed, no abrasion, high working reliability, lower water cooling requirement, good vacuum sealing and the like;

3. the capacitor rotor is connected with the power connection turntable through the power connection copper net in a pressing mode to be in electric contact with the power connection turntable, and the power connection copper net has certain deformability; the stability of electric contact between the capacitor rotor and the power connection turntable is ensured.

Drawings

FIG. 1 is a schematic diagram of the structure of a cavity of a synchrocyclotron;

FIG. 2 is a schematic structural diagram of a capacitor rotor according to the present embodiment;

FIG. 3 is a schematic structural view of an electrical contact structure in the present embodiment;

fig. 4 is an enlarged schematic view of a in fig. 3.

Description of reference numerals: 1. a main vacuum chamber; 2. a capacitive vacuum chamber; 3. a Dee plate; 4. a capacitor stator; 5. a capacitive rotor; 51. a disk portion; 52. a blade section; 53. the connecting circular hole; 54. an annular groove; 6. a rotating shaft; 61. connecting the bosses; 62. connecting a power turntable; 7. connecting a copper net; 8. a planar narrow gap; 9. a magnetic fluid seal; 10. a ceramic bearing.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

In the embodiment, a specific structure of an electrical contact structure of a rotating capacitor rotor in a synchrocyclotron is described by taking a medical synchrocyclotron as an example, and the electrical contact structure of the rotating capacitor rotor is applied to the electrical contact method of the rotating capacitor rotor in the synchrocyclotron.

The synchrocyclotron obtains the frequency of 60MHz-85MHz by adopting a variable capacitance mode, and the design value of the modulation frequency is 1 kHz. Wherein the ion acceleration time is 0.328 ms. FIG. 1 is a schematic diagram of a cavity structure of a synchrocyclotron, which adopts a half-wavelength structure; the vacuum capacitor comprises a main vacuum chamber 1 arranged at the head part and a capacitor vacuum chamber 2 arranged at the tail part, wherein a Dee plate 3 is arranged in the main vacuum chamber 1, and the head end of the Dee plate 3 and the inner wall of the main vacuum chamber 1 are arranged at intervals to form an equivalent capacitor; the capacitor vacuum chamber 2 comprises a capacitor stator 4 which is fixedly arranged in the capacitor vacuum chamber 2 and is provided with two layers of blades, a capacitor rotor 5 which is rotationally connected with the capacitor vacuum chamber 2 and is provided with one layer of blades, and a rotating shaft 6 for driving the capacitor to rotate. Wherein, one layer of blades of the capacitor rotor 5 is arranged between two layers of blades of the capacitor stator 4 to form a rotating capacitor; and the Dee plate 3 is connected with the capacitor stator 4 through a transmission line to form equivalent adjustment of equivalent capacitance and rotating capacitance frequency.

As known in the art, in order to adapt to relativistic influences, the frequency of the synchrocyclotron needs to be gradually reduced during the ion acceleration process. The rotating capacitor can change the area opposite to the blades of the capacitor stator 4 through the rotation of the capacitor rotor 5; the frequency modulation of the rotating capacitor and the equivalent capacitor is realized.

It should be noted that the electric contact structure of the capacitor rotor 5 in the present embodiment only includes the capacitor vacuum chamber 2, the capacitor rotor 5 and the rotating shaft 6. The main vacuum chamber 1, the Dee plate 3 and the capacitor stator 4 are not within the scope of the present solution, and are understood as the prior art solution, so the details are not described herein.

As shown in fig. 2, the capacitor rotor 5 includes a disk portion 51 provided at the center portion and blade portions 52 distributed along the circumferential outer side of the disk portion 51. The thickness of the disc part 51 is equal to that of the blade part 52 and is 5mm, so that the disc part 51 and the blade part 52 can be machined by using the same copper plate, the machining process is convenient, and copper materials are not wasted. Specifically, in the present embodiment, the number of the blade portions 52 is 8, and in order to improve the connection strength between the disk portion 51 and the blade portions 52, eight threaded holes are uniformly distributed in the disk portion 51 along the circumferential direction, so that the blade portions 52 are fastened to the disk portion 51 by screws. It should be noted that in the present embodiment, an end surface of the blade portion 52 away from the disc portion 51 is set to be an eccentric arc shape, and the shape is processed by a linear cutting technique according to a cavity frequency modulation algorithm (specifically, refer to chinese patent publication No. CN 105376925 a), so as to ensure symmetry of the rotating capacitor rotor 5 and reduce eccentricity or vibration during high-speed rotation.

Furthermore, a connecting circular hole 53 is formed in the center of the disc part 51, a connecting boss 61 inserted into the connecting circular hole 53 extends from one end of the rotating shaft 6 facing the disc part 51, the axial length of the connecting boss 61 is equal to the thickness of the disc part 51, and good electrical contact is guaranteed. Specifically, after the connecting boss 61 penetrates into the connecting circular hole 53, the connecting boss 61 is fixed by installing a screw, and the diameter of the connecting circular hole 53 in the present embodiment ranges from 9 to 10.5mm, and preferably ranges from 10 mm. If the size of the connecting circular hole 53 is too small, the capacitor rotor 5 and the rotating shaft 6 are not fastened and contacted sufficiently at the central position; if the machining deviation is too large, the machining deviation is amplified, the precision is not easy to control, and misalignment of the capacitor rotor 5 and the rotating shaft 6 can be caused.

The rotating shaft 6 is provided with an electric connection turntable 62 which is separated from the disc part 51, the electric connection turntable 62 is arranged in the capacitance vacuum chamber 2, and an electric connection copper net 7 is pressed between the disc part 51 and the electric connection turntable 62; specifically, an annular groove 54 is formed in one side of the disc part 51 facing the power connection turntable 62, the power connection copper mesh 7 is annular, one end of the power connection copper mesh 7 is embedded into the annular groove 54, and the other end of the power connection copper mesh abuts against the power connection turntable 62. The contact copper grid 7 is elastic, and when the contact copper grid 7 is not deformed, the outer circle radius of the annular groove 54 contacting the radius of the contact copper grid 7 is larger than the outer circle radius of the annular groove 54. The electrified copper mesh 7 has certain deformability. The power connection copper net 7 is fixed in a pressed mode, friction between the power connection copper net 7 and the annular groove 54 is increased, electric connection of the disc part 51 and the power connection rotary disc 62 in surface contact is guaranteed, and meanwhile stability of the position of the power connection copper net 7 is guaranteed.

Preferably, the electrified copper mesh 7 is a beryllium copper mesh. The beryllium copper wire mesh has better conductivity in the copper wire mesh, and can effectively reduce contact resistance.

Furthermore, the rotating shaft 6 and the power receiving turntable 62 are detachably connected. Specifically, a knife edge is arranged on one side of the rotating shaft 6, which is connected with the electric rotating disc 62, the knife edge is 0.5mm wide, and the inclination angle is 45 degrees. The electric connection rotary disc 62 is matched with the knife edge in a sleeved mode and fixed through screws, and electric connection between the electric connection rotary disc and the rotating shaft 6 is achieved.

As known in the art, the housing of the capacitor vacuum chamber 2 is at ground potential, and the short-circuit end generally refers to a place where a high-potential conductor in the cavity of the capacitor vacuum chamber 2 is connected to the housing of the capacitor vacuum chamber 2 (i.e., a place where the high-potential conductor is connected to the power-receiving turntable 62 in the present embodiment), where the voltage is approximately zero and the current is the largest. The high voltage end of the conductor in the capacitance vacuum chamber 2 has the maximum voltage and the current is approximately zero.

Therefore, the capacitor vacuum chamber 2 is provided with a plane parallel to the power receiving turntable 62 on the side of the power receiving turntable 62 away from the disk part 51, the plane constituting a short-circuit end. A planar narrow gap 8 is provided between the short-circuit end and the electrical connection turntable 62, the planar narrow gap 8 being smaller than 0.2 mm. Measuring the flatness of the short-circuit end surface of the rotating shaft 6 by using a dial indicator, and measuring the flatness to be superior to 0.03mm after correction; a plane narrow gap 8 between a turntable of the rotating shaft 6 and a short circuit end of the rotating shaft 6 is measured by using a feeler gauge, and the gap is measured to be 0.1mm after correction. The two modifications and measurements ensure that the opposite surfaces of the electrical connection turntable 62 and the short circuit end are not in contact during the rotation of the rotating shaft 6. So that a grounded capacitor is formed between the power connection turntable 62 and the short-circuit end. And because the grounding capacitor belongs to the high-frequency field, the resistance value of the capacitor is very low (approximate to 0) in the high-frequency field, thereby realizing high-frequency grounding.

Furthermore, a magnetic fluid sealing member 9 for the rotation shaft 6 to penetrate is fixedly connected to the end surface of one side of the capacitance vacuum chamber 2 far away from the capacitance rotor 5. It should be appreciated that the magnetic fluid seal 9 is one type of rotary seal that utilizes the fluidity and magnetic permeability of the magnetic fluid material to effect the seal, and is an existing component. The size of the magnetic fluid seal 9 can be adjusted according to the structure of the capacitance vacuum chamber 2. The magnetic fluid sealing element 9 is connected with the capacitance vacuum chamber 2 through a flange, and an O-shaped ring is filled between the connection part of the magnetic fluid sealing element 9 and the capacitance vacuum chamber 2 to ensure the connection tightness. The rotating speed of the rotating shaft 6 in the magnetic fluid sealing element 9 can reach 7500 rpm, and a water cooling loop is designed on the magnetic fluid sealing element 9, so that the sealing effect failure caused by overheating of the magnetic fluid under the condition of high rotating speed is avoided.

In addition, in order to ensure that the rotating shaft 6 is not in direct electrical contact with the shell of the magnetic fluid sealing element 9 and the shell of the capacitance vacuum chamber 2 respectively; in the scheme, the ceramic bearing 10 made of alumina is adopted in the magnetic fluid sealing element 9, and the surface of the rotating shaft 6 is also sprayed with the alumina.

In conclusion, the design firstly ensures that the capacitor rotor 5 is not in direct contact with the cavity shell; in addition, a narrow gap 8 between the turntable of the rotating shaft 6 and the short-circuit end of the capacitance vacuum chamber 2 is utilized to form a grounding capacitor, so that grounding in a high-frequency state is realized. The problem that the electric contact is failed under the condition that the capacitor rotor 5 rotates at high speed by the brush technology is avoided. Through tests, the unloaded quality factor of the cavity of the synchrocyclotron model in a frequency range of 60-85 MHz is 1600-1800, and the level of usable orders of magnitude is reached.

The cavity frequency modulation method of the synchrocyclotron is not limited to the above specific embodiments, and those skilled in the art can derive other embodiments according to the technical solution of the present invention, and the method also belongs to the technical innovation scope of the present invention.

Claims

1. An electrical contact method for a rotating capacitor rotor in a synchrocyclotron is characterized in that: the electric contact method is applied to an electric contact device for rotating a capacitor rotor, the electric contact device comprises a capacitor vacuum chamber (2), the capacitor rotor (5) rotatably arranged in the capacitor vacuum chamber (2) and a rotating shaft (6) fixedly connected to one end of the capacitor rotor (5) and used for driving the capacitor rotor (5) to rotate, and the capacitor rotor (5) comprises a disk part (51) arranged in the middle and blade parts (52) distributed along the circumferential outer side of the disk part (51);

the electric contact method comprises the following steps:

the rotating shaft (6) is provided with an electricity connection rotating disc (62) which is spaced from the disc part (51), an electricity connection copper net (7) is pressed between the disc part (51) and the electricity connection rotating disc (62), one side, facing the electricity connection rotating disc (62), of the disc part (51) is provided with an annular groove (54), the electricity connection copper net (7) is annular, one end of the electricity connection copper net (7) is embedded into the annular groove (54), and the other end of the electricity connection copper net abuts against the electricity connection rotating disc (62); electrically contacting the rotating shaft (6) with the capacitor rotor (5); and

a plane parallel to the power connection rotary disc (62) is arranged on one side, away from the disc part (51), of the power connection rotary disc (62) in the capacitance vacuum chamber (2), the plane forms a short-circuit end, a plane narrow gap (8) used for high-frequency grounding is arranged between the short-circuit end and the power connection rotary disc (62), and the plane narrow gap (8) is smaller than 0.2 mm; the opposite surfaces of the electric connection turntable (62) and the short circuit end are not contacted; a grounding capacitor is formed between the electric connection turntable (62) and the short-circuit end; the resistance value of the grounding capacitor is close to zero under high-frequency current, so that the cavity shell of the electric connection turntable (62) and the capacitor vacuum chamber (2) are commonly at the ground potential.

2. A method of electrically contacting a rotating capacitor rotor as recited in claim 1, wherein: the electric copper connecting net (7) is elastic, and when the electric copper connecting net (7) is not deformed, the outer circle radius of the annular groove (54) of the radius of the electric copper connecting net (7) is larger than the outer circle radius of the annular groove.

3. A method of electrically contacting a rotating capacitor rotor as claimed in claim 1 or 2, wherein: the power connection copper mesh (7) is a beryllium copper mesh.

4. A method of electrically contacting a rotating capacitor rotor as recited in claim 1, wherein: and one side of the capacitance vacuum chamber (2) is fixedly connected with a magnetic fluid sealing element (9) for the rotating shaft (6) to penetrate through.

5. A method of electrically contacting a rotating capacitor rotor as recited in claim 1, wherein: the surface of the rotating shaft (6) is sprayed with alumina ceramics.

6. A method of electrically contacting a rotating capacitor rotor as recited in claim 1, wherein: the round connection hole (53) has been seted up to disc portion (51), pivot (6) are provided with connection boss (61) that the tight fit connected in connecting round hole (53) towards disc portion (51) one end, the axial length of connecting boss (61) and connecting round hole (53) equals.

7. A method of electrically contacting a rotating capacitor rotor as claimed in claim 1 or 6, wherein: the disk part (51) and the blade part (52) have the same thickness.

8. A method of electrically contacting a rotating capacitor rotor as defined in claim 6, wherein: the diameter of the connecting round hole (53) is 9-10.5 mm.