JP2004530260A - Multi-stage cavity cyclotron resonance accelerator - Google Patents

Abstract

High-current, high-gradient, high-efficiency multistage cavity cyclotron resonance accelerators (MCCRAs) provide energy gains of over 50 MeV / stage with room temperature cavities with acceleration gradients over 20 MeV / m. The multi-cavity cyclotron resonance accelerator includes a charged particle source, a plurality of end-to-end rotational mode room temperature cavities, and provides a substantially uniform magnetic field through the cavities. In particular, the MCCRA is provided with a constant magnetic field sufficient to generate a cyclotron frequency slightly higher than the acceleration field RF. A plurality of input feeds, each coupled to the cavity, are also provided. According to an embodiment of the present invention, the beam from the first cavity passes through the cutoff drift tube and is further accelerated in the cavity, which still supports a low radio frequency electric field. This embodiment efficiently produces a 1 gigavolt proton beam of several milliamps. A single cavity transfers about 70% of the radio frequency energy to the beam. Cuts between cavities operating at progressively decreasing frequencies, each slightly lower than the local relativistic cycloton frequency of the beam in the cavities, using a static magnetic field that is constant or slightly reduced along its length Multi-cavity accelerators using off-drift tubes provide a very efficient, compact and continuously operating intermediate energy accelerator. In another embodiment of the invention, the progressively decreasing frequency is selected to decrease in substantially equal increments corresponding to different frequencies. Charged particles are emitted in pulses corresponding to different frequencies.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to charged particle accelerators, and more particularly to cyclotron resonance accelerators having a number of hollow stages to substantially increase efficiency and having a uniform magnetic field across each of the stages.
[0002]
[Prior art]
There are several applications for charged particle accelerators that generate particles having energy equal to about two or three times the resting mass energy. For example, when electrons (static mass equal to 0.511 MeV) are accelerated at one million volts, the properties of the rock, a property important in determining whether the rock is porous enough to contain oil, are important properties. Generate X-rays with the appropriate energy to determine. Millions to millions of electron volts are also appropriate energy for X-rays used in the sterilization of foodstuffs, for example to safeguard against E. coli, Salmonella, Listeria contamination. When protons (static mass equal to 938 MeV) are accelerated to about 1 billion volts, they have a large cross section that generates neutrons when they impact heavy metal nuclei such as lead, mercury or tungsten. These neutrons can drive a subcritical reactor. Such sub-critical reactors more efficiently use fissionable nuclear fuel, consume long-lived actinides, and thus reduce the geological storage problems associated with normal reactor waste. In these accelerator applications, it is not important to focus the particle beam on a small spot, as in imaging an X-ray tube. In these applications, the diffusion shock zone is advantageous because it facilitates solving thermal problems that would otherwise be difficult.
[0003]
For high energy devices, linear acceleration is convenient because losses are reduced by cyclotron radiation. In high current devices, linear accelerators are useful because the beam loading in each cavity is large compared to the losses in the cavity due to the electrical resistance of the cavity material. This is especially true in pulsed devices where cavity losses are minimized by turning off tuning of RF power between high current beam pulses. For devices that use continuous current where there is a requirement for a well-focused beam with low divergence, the beam load is very small, so a superconducting cavity must be used to solve the cavity loss problem. No. Alternatively, a circular device in which the beam orbits the same cavity multiple times is more efficient because the beam load is increased in terms of losses in proportion to the number of beams passing through the cavity. The problem with circular devices is that the cyclotron frequency changes as the relativistic mass of the particle changes with energy. Usually, particles are accelerated as long as the frequency of the acceleration voltage is lower than the relativistic cyclotron frequency of the particles in the magnetic field. When a particle gains energy, the relativistic cyclotron frequency falls below the frequency of the "acceleration" voltage, and the particle returns some of its energy to the "acceleration" electric field.
[0004]
In 1945, Veksler of the Soviet Union and McMillan of the country pointed out that relativistic particles tend to "bunch" and remain stable with respect to the phase of the accelerating voltage. Thus, the energy limitation imposed by changing the cyclotron frequency due to the energy in a normal cyclotron can be addressed by changing the frequency of the accelerating voltage or the magnetic field as done in the synchrocyclotron or synchrotron, respectively. it can. If these changes occur slowly enough, the charged particles gain energy as the frequency is reduced or the magnetic field is increased. Such a beam is not continuous, but instead is extracted from the device after the desired energy has been reached.
[0005]
In 1958 and 1959, Twiss, Gaponov, and Schneider reported that a transverse RF electric field and electrons traveling along a helical path with a constant axial magnetic field caused azimuth by a mechanism of relativistic mass change. I realized that it would be a bunch. They also radiate at frequencies close to the cyclotron frequency. This interaction is sometimes called "cyclotron resonance maser" (CRM) instability. Hirshfield and Wachtel, co-inventors of Yale University, observed CRM instability and calculated its properties. It is probably correct to consider CRM instability as the reciprocal of synchrotron acceleration due to the addition of axial motion to the electrons. Jory and Trivelpies are TE₁₁₁ Electrons having an energy of 1000 volts conducted along the axis of the circular waveguide cavity were accelerated to an energy of 500,000 volts having mainly momentum directed toward the periphery. They used these electrons to generate millimeter-wavelength radiation in another circular waveguide that supported higher-order modes.
[0006]
More recently, Hirshfield has constructed a more sophisticated inverse CRM accelerator. He has a magnetic field of TE₁₁Configures an electron accelerator similar to device 1 described above except that it increases along the axis of the waveguide supporting modes, whereby the Doppler shifted RF field maintains synchronization with the relativistic cyclotron frequency did. This type of device is called a cyclotron automatic resonance accelerator (CARA). Wang and Hirshfield have developed the computer code necessary to simulate the movement of charged particles in static and high frequency fields. Hirshfield and LaPointe first attempted electronic CARA. The results showed that energy equal to twice the resting mass energy was reached with a achievable field intensity, but efficiency was not significant. Simulating for protons was a very disappointing result. The proton particles made very few orbits in the magnetic field before mirroring occurred. Since the axial magnetic field of CARA increases with axial distance, a radial magnetic field must be present. This interacts with the angular velocity of the particles, resulting in stopping the beam and sending it back along the axis. In CARA for protons, it has been found that if the electric field and the resulting losses in the cavity are not very high, the protons will stop before making enough orbits to get close to the desired energy.
[0007]
[Problems to be solved by the invention]
Accordingly, it would be advantageous to provide an accelerator that does not suffer from the stall problem of known cyclotron automatic resonance accelerators and that can accelerate particles with high efficiency to energy equal to at least twice its stationary mass.
[0008]
[Means for Solving the Problems]
In accordance with the teachings of the present invention, a high current, high gradient, high efficiency, multi-stage cavity cyclotron resonance accelerator (MCCRA) provides an energy gain of over 50 MeV / stage with an acceleration gradient of over 20 MeV / m in a room temperature cavity.
[0009]
A multi-cavity cyclotron resonance accelerator includes a charged particle source, a plurality of end-to-end rotational mode room temperature cavities, and a solenoid coil. A solenoid coil surrounds the cavity and provides a substantially uniform magnetic field through the cavity. In particular, the MCCRA is provided with a constant magnetic field sufficient to generate a cyclotron frequency slightly higher than the acceleration field RF. A plurality of input feeds, each coupled to the cavity, are also provided. According to an embodiment of the present invention, the beam from the first cavity passes through the cutoff drift tube and is further accelerated in a cavity that still supports a low radio frequency electric field. This embodiment produces a proton beam with a current greater than 100 mA. A single cavity transfers about 70% of the radio frequency energy to the beam. Cutoff drift between cavities operating at progressively lower frequencies, each slightly lower than the local relativistic cycloton frequency of the beam in the cavities, using a static magnetic field that is constant or slightly reduced along its length Multi-cavity accelerators using tubes provide a very efficient, compact and continuously operating medium energy accelerator.
[0010]
The accelerator field is substantially uniform across all stages because the increased magnetic field leads to unwanted loss and stall of axial momentum, and the reduced magnetic field leads to an unmanageable increase in the orbital radius. The successively arranged cavity stages of the accelerator operate at continuously lower RF frequencies so as to maintain near resonance as the mass of the particles increases. In one embodiment of the invention, progressively lower frequencies are selected to decrease in substantially equal increments corresponding to the difference frequency. Charged particles are emitted in pulses corresponding to different frequencies.
[0011]
A more complete understanding of a multi-cavity cyclotron resonance accelerator (MCCRA) will be given to those of ordinary skill in the art, as well as its additional advantages and objects, by considering the following detailed description of the preferred embodiments. First, a brief description will be given with reference to the accompanying drawings.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention relates to a high current, high gradient, high efficiency, multi-cavity cyclotron resonance accelerator (MCCRA). MCCRA provides energy gains of over 50 MeV / stage with acceleration gradients of over 20 MeV / m. A current accelerated above 100 mA can obtain a pulse of more than enough microseconds without microbunch. Acceleration is provided by cyclotron resonance, thus requiring a strong static magnetic field.
[0013]
One exemplary RF structure of a multi-stage high gradient cavity proton accelerator is shown in FIG. Accelerator is ion source 1, end-to-end TE₁₁₁ The rotation mode room temperature cavities 2 and 3 and the solenoid coil 4 are included. Input feeds 6, 7 are coupled to cavities 2, 3, respectively. Solenoid coil 4 provides a substantially uniform magnetic field passing through cavities 2,3. The DC voltage power supply 8 supplies an acceleration voltage of about several kilovolts to the ion source 1. The magnetic field in the accelerator traverses all stages because the increasing magnetic field leads to undesired loss of axial momentum and stall, while the decreasing magnetic field leads to an unmanageable increase in the orbital radius of the charged particles. And be substantially uniform. It will be appreciated that the accelerator shown in FIG. 1 has been simplified for ease of explanation, and that an actual accelerator may have more cavity stages than the two shown in the drawing. Should.
[0014]
In one embodiment of the present invention, the first cavity 2 has a frequency of 100 MHz (f₁ ) At 10 MW RF power and the second cavity 3 is 94 MHz (f₂ ) Is driven at 7.7 MW. It is important that the successively arranged cavity stages of the accelerator operate at continuously lower RF frequencies to maintain an approximate resonance as the particle mass increases. Acceleration of particles from 10 keV to 1 GeV requires a reduction of the aggregation frequency between the first and last cavity states by a factor of about 2. This decrease in frequency is the opposite of the typical temporarily increasing frequency change for a synchrotron, in which case the magnetic field also increases.
[0015]
In an embodiment of the present invention, the unloaded (ie, ohmic and external) and beam-loaded quality factor for the first cavity is Q₀ = 100,000 and Q_L = 30,000, while in the second cavity these are Q₀ = 100,000 and Q_L = 17,000. These values indicate that 70% of the incident RF power is absorbed by the proton beam in the first cavity 2 and 83% is absorbed by the proton beam in the second cavity 3. The beam power after the second stage is 13.4 MW. A uniform magnetic field of 67.0 kG passes through both cavities. The injected proton beam energy is 10 keV, the final proton energy is 114.0 MeV, and the proton current is 117.6 mA. For the purposes of this description, it is assumed that the beam has zero starting radiation and zero starting energy spread. Sixteen computed particles to simulate the beam are injected at a 1.25 ns time interval corresponding to a 20 ns pulse width and a π / 4 RF phase period over two cycles at 100 MHz. The injected particles have zero starting radial coordinates.
[0016]
The history of the change in average energy gain and axial velocity along the first cavity is the three values B of the axial guide field._Z = 66.8, 67.0, 67.2 kG are shown in FIG. <Γ> = 1 + (/ U) [MeV] / 938, and the average shaft speed <B_Z > = (/ V_Z The calculated change in average proton energy in units of) / c is shown as a function of the axial coordinate z in the first cavity. As described in the text, examples of parameters and three values of the B field are shown. The first cavity has a radius of 110 cm, the energy gain at the rear end of the cavity (z = 250 cm) is a maximum at 67.0 kG, and the decrease in axial velocity in the cavity is as severe as at 67.2 kG. is not. Further B_Z Has been found to lead to a reversal of the sign of the axial velocity, ie the reflection of the particles. This stall effect is due to the ponderromotive axial force, which is clearly based on the exact details of the proton orbit. B_Z = 67.0 kG, the substantial energy gain (/ U)-(/ U) due to only a small temporary decrease in axial velocity₀ ) = 59.5 MeV (γ = 1.0063) was found during passage through the cavity, where (/ U) and (/ U)₀ ) Is the collective average of the last and first proton energies, respectively. Because the proton cyclotron frequency drops below 94% of the RF frequency at this stage, for z> 200 cm, the small decrease in particle energy is due to excessive phase slip. The average acceleration gradient in the first cavity is 23.8 MeV / m. At a beam current of 117.6 mA, the efficiency of the first cavity is 70%. Strong axial acceleration gradients are possible because the protons create a large number of gyrations and follow long paths that travel almost parallel to the rotating RF field. In this example, the protons perform about 48 revolutions in the first cavity, eventually reaching a gyration radius of about 17 cm. TE with uniform magnetic field₁₁₁ This rapid and efficient cyclotron resonance acceleration of protons in the cavity shows results similar to those reported electronically by Jory and Trivelpiece, which showed evidence of acceleration by several hundred KeV.
[0017]
FIG. 3a shows the energy gain and axial velocity of two exemplary cavities operating in cascade. A second cavity operating at 94 GHz has a radius of 110 cm and a length of 302 cm. It has been found that the relative phase difference between the fields in the first and second cavities (calculated at the start) is set to 0.70π, the value of which maximizes the energy gain in the second cavity. ing. This phase difference allows the gyration protons to enter the second cavity with velocity vectors aligned substantially parallel to the rotating RF field for maximum energy gain. From FIG. 3a, it can be seen that the energy gain of both cavities reaches 113.96 MeV (γ = 1.1215) and the axial velocity remains almost constant through the second cavity. Beam-loaded Q (17,000) and RF drive power (7.7 MW) were adjusted to match the same current (117,6 mA) as the first cavity. The protons perform about 43 rotations in the second cavity, eventually reaching a gyration radius of about 22 cm. The average acceleration gradient in both cavities is 20.7 MeV / m. FIGS. 3b and 3c show projections of the transverse (xy) and longitudinal (xz) planes of the orbit of a single proton during the acceleration period. In particular, FIG. 3b shows a lateral plane projection of the trajectory of a proton undergoing acceleration as in FIG. 3a. FIG. 3c shows a projection in the vertical plane of the orbit of a proton undergoing acceleration as in FIGS. 3a and 3b. The proton makes about 90 revolutions during the acceleration period.
[0018]
The same principles illustrated in the above examples for proton acceleration can be applied to the acceleration of other charged particle species, ie, electrons, muons, or heavy ions. In view of the present biggest problem of muon accelerators, an alternative embodiment of the present invention can perform muon acceleration at cyclotron resonance using a strong uniform magnetic field cavity. FIG. 4 shows an example of two cavities in a uniform 67.0 kG B-field for the following parameters:
First cavity: f = 850 MHz, P = 10 MW, Q₀ = 40.000, Q_L = 20,000, R = 13 cm, L = 29 cm;
Second cavity: f = 700 MHz, P = 4.0 MW, Q₀ = 40.000, Q_L = 10,000, R = 15cm, L = 39cm
The acceleration in the first cavity is from 10 KeV to 23.24 MeV and in the second cavity it is accelerated to 37.1 MeV. The beam current is 215 mA, the maximum orbit radius is 3.8 cm, the average acceleration gradient is 54.4 MeV / m, and the overall efficiency is 57%. These values are preferable as compared with a conventional Mulon linear accelerator.
[0019]
100 MHz and 94 MHz TE for the first two stage example of the proton accelerator shown in FIGS. 2-4₁₁₁ The cavity has a diameter of 220 cm and the maximum proton orbital diameters are 34 cm and 44 cm. At least in these first stages, most of the cavity volume is not traversed by the proton beam, but is permeated by flux lines from the surrounding solenoid coils. The required 67 kG cyclomagnet would probably require a 240 cm bore at room temperature (to allow space for the RF feed as shown in FIG. 1). While this is probably within the current state of the art, reducing this caliber is highly desirable.
[0020]
In a first alternative embodiment, shown in FIG. 5, the diameter of the cavity is reduced by using a dielectric load in the form of a thick coaxial dielectric liner 9,10. HEM₁₁In the analysis of the mode dispersion relation, for example, TE₁₁It has been shown that a 100 MHz cavity with a field-like shape has a greatly reduced overall diameter. With an alumina dielectric (ε = 9.6), a hole diameter of 40 cm and a cavity length of 250 cm, the outer diameter is about 84 cm. As the resonant frequency decreases and the diameter of those holes increases to accommodate the increased radius of the gyration beam, the continuum is of course larger. A disadvantage of the presence of alumina in the high power cavity structure is that it creates a failure problem, and the large weight and cost of such large alumina elements is also disadvantageous.
[0021]
In a second alternative embodiment, shown in FIG. 6, a thick radial wing 62 is used in a capacitively loaded cavity, thereby reducing the cutoff frequency for the desired dipole mode. It should be noted that only half of the structure after being cut along the vertical axis of symmetry is shown in FIG. When four symmetric wings are used, the two dipole modes are 90 ° time and spatially out of phase with respect to each other. To obtain a rotated (ie circularly polarized) field, these two dipole modes are excited in the time quadrant. This structure can be called a radio frequency double dipole (RFDD). A simple example of the RFDD structure was analyzed using a simulation code for the HFSS structure, and the results are shown and configured in FIG. It can be seen that the field lines in the polar mode are nearly uniform near the axis.
[0022]
The RFDD structure shown in FIG. 6 was found to have an outer diameter of 130 cm, a ridge width of 15 cm, a center gap between opposing ridges of 30 cm, and a cutoff frequency of the dipole mode of 73.8 MHz, while , The cutoff frequency of the quadrupole mode was found to be 78.97 MHz. Thus, a 222 cm long section of the RFDD structure has a dipole resonance frequency of 100 MHz and a quadrupole resonance frequency of 104 MHz. Q of about 1,000-10,000_L The operation at is thus made purely possible in dipole mode without coupling much into the quadrupole mode by the beam. Simple TE₁₁₁ This ideal example is given to illustrate the possibility of developing an all-metal structure device for the proton cyclotron accelerator cavity, which has a significantly smaller outer diameter than the cylindrical cavity. The analysis of the RFDD structure is further advanced by optimizing the shape of the wings, rounding the sharp corners to reduce the surface magnetic field strength, and coupling the input to excite both degenerate dipole modes in the time quadrant. It is expected that giving is included. The optimized design of a two-cavity structure based on RFDD also aims to perform a study of the proton acceleration in the actual RF field of the structure using the particle simulation code KARAT in the cell. Once the optimized structure is found, a cold test model is assembled and scaled to the S band for experimental testing to ensure the design.
[0023]
As mentioned above, proton is one TE₁₁₁ Drift from one cavity to the next, but because the applied axial magnetic field is uniform and the effective proton mass is increasing, the cavities continuously arranged to provide cumulative acceleration have low resonance frequencies. Must have With a single narrow bunch of protons, it is not difficult to imagine acceleration through the cascade of cavities if the phase of the field in each cavity is properly adjusted. Especially when the proton bunch arrives at each cavity, the rotating TE₁₁₁ Maximum acceleration is achieved if the direction of the mode's electric vector is parallel to the proton moment. However, the uniform acceleration of the proton bunch array wisely arranges the different frequency phases of successively placed cavities to ensure that all bunches have the same history as they progress through the cascade. Occurs only when
[0024]
In another embodiment of the invention, the cavity frequencies are aligned to decrease in equal increments. For example, the frequency increment may be selected to be 5 MHz and the cavity frequency may be selected to be 100, 95, 90, 85... 50 MHz. The proton beam is pulsed between successive cavities at a difference frequency (eg, 5 MHz) such that a proton bunch enters each cavity at a time, where the electromagnetic fields of the cavities are aligned in some way. In particular, the initial phase of the field in each cavity may thus be aligned to provide an optimized cumulative acceleration to the first proton bunch. A continuous bunch is the inverse of the difference frequency (eg, 5^-1MHz or 200 nanoseconds), the field seen by each bunch is identical to the field seen by the first bunch. This means that after each 200 nanosecond interval, the field in each cavity has been advanced exactly 20, 19, 18, 17, 16,... 10 cycles, thus reconstructing the sequence seen by the first bunch. Because. Since accurate reconstruction according to this example only occurs at 200 nanosecond intervals, protons in a finite width bunch will experience a slightly different acceleration history, leading to a finite energy spread of the bunch. It is expected that this diffusion can be minimized by judicious selection of the average phase difference between successively placed cavities. Further, the phases can be concentrated. In these respects, the cascade of cavities has features in common with conventional RF linacs, i.e. linear accelerators that generate a high energy level particle beam by propelling particles linearly with energy from an electromagnetic field, such as a linac. Have.
[0025]
In order for the cavities to maintain the desired frequency spacing, it is important to control the amount of power provided to each cavity for a given beam current. FIG. 7 is a table showing the power calculations of eleven cavity accelerators having spaced cavity frequencies as described in the previous example. For each cavity, the table shows the initial and final proton energy (γ), proton velocity (β), beam loading, total beam power, and orbital radius. At the beam power levels identified in this table, the cyclotron frequency is closest to the cavity frequency at any point in the device.
[0026]
FIG. 8 shows the effect of a finite proton bunch width. In the first cavity, the acceleration is independent of the injection time. However, the energy spread increases with the pulse width because the acceleration of the second cavity is phase dependent. In this example, the parameters for the 100 MHz first cavity are similar to those described above with respect to FIGS. 2-3c. In the second cavity at 94 MHz, Q_L And parameters except for small changes in the final average beam energy. For the example of 5, 10, 20 nanoseconds, Q_L Are 13,200, 13,600, and 17,000, respectively, and the final average beam energies are 116.2, 116.0, and 114.0 MeV, respectively. The relative starting phase difference between the fields in the two cavities is 0.70π. For 5 nanoseconds, the final energy spread is about 2%.
[0027]
FIG. 9 shows the effect of the relative phase difference on the beam energy spread. For a pulse width of 5 nanoseconds (ie, a duty factor of 3%), the acceleration history and evolution of the beam rms energy spread are shown for three values of relative phase shift: 0.65π, 0.70π, 0.75π. Have been. A final rms energy spread of about 0.7% is seen at 0.75π, which can be seen to be approximately three times lower than at 0.70π. Q of the second cavity_L Are 16.500, 13.200, and 11.600, respectively, and the final average beam energies are 114.2, 116.2, and 117.3 MeV, respectively. Significant reduction in energy spread after an axis length z of about 500 cm, with minimal spread associated with maximum final energy, strongly suggests that longitudinal phase focusing has occurred. I have. This phenomenon is sensitive to small changes in the relative phase between the cavities.
[0028]
It is also beneficial to show the bunch shape during acceleration. While FIGS. 3b and 3c show typical proton orbitals, the instantaneous distribution of charged particles of a finite length bunch is such that the continuous proton orbits are in the xy plane at RF frequencies. Because it is rotated, it does not lie along this curve. For illustration, FIGS. 10a and 10b show a 5 ns length at the moment the bunch head reaches the end of the first cavity (z = 249.06 cm) (ie, 671.5 ns after injection). The positions in the xz and yz planes of 16 protons injected into an axis with a bunch of. The particles appear to lie along an approximately straight line about 4.8 cm in length, with deviations from linearity less than 0.4 mm. The positions of these particles can be contrasted with the traces in the xz plane of the first particles during the final 4.8 cm travel, which has a radius of about This is a half cycle of vibration of 17 cm. During acceleration, the proton bunch advances in the z-direction and rotates about the z-axis as a straight, rigid object. Small deviations from linearity result from the phase slip between the proton moment and the RF field and the small energy difference between the bunch head and tail. Approximate uniformity of axial charged particle dispersion in such a long bunch mitigates longitudinal instability.
[0029]
While the preferred embodiment of the multi-cavity cyclotron resonance accelerator has been described above, it will be apparent to those skilled in the art that superior advantages over the prior art have been realized. Obviously, various modifications, adaptations, and alternative embodiments may be made within the scope of the present invention. The invention is further limited by the claims.
[Brief description of the drawings]
FIG.
FIG. 3 is a diagram showing two stages of a multistage high gradient cavity proton accelerator.
FIG. 2
FIG. 4 shows the calculated change in average proton energy.
FIG. 3
FIG. 3 shows the energy gain of protons in two passing cavities, the projection of a transverse plane of the orbit of a proton undergoing acceleration, and the projection of a longitudinal plane of the orbit of a proton undergoing acceleration.
FIG. 4
FIG. 4 shows the normalized average energy and axial velocity of muons in a two-cavity cyclotron accelerator.
FIG. 5
The figure which showed an example of the accelerator which has a coaxial dielectric liner.
FIG. 6
The figure which showed an example of the cross section of the 4-blade RFDD structure of a proton cyclotron accelerator.
FIG. 7
FIG. 4 is a diagram illustrating a calculation of the power of 11 cavity accelerators having spaced cavity frequencies. FIG.
FIG. 8
The figure which showed the influence of the finite bunch width in rms energy diffusion.
FIG. 9
FIG. 3 shows acceleration history and evolution of rms energy diffused by a two-cavity proton accelerator for three values of the relative starting phase between the two-cavity fields.
FIG. 10
FIG. 6 shows the position of the 5-nanosecond bunch proton at the end of the first cavity in the xy and yz planes.

Claims (16)

In a high current, high gradient, high efficiency, multi-cavity cyclotron resonance accelerator (MCCRA) for accelerating charged particles,
A charged particle source that emits a pulse of the charged particles;
A plurality of sequentially arranged rotational mode cavities extending axially and coupled to the charged particle source;
At least one solenoid coil disposed coaxially about the cavity and providing a substantially uniform magnetic field along an axial extent of the plurality of sequentially disposed cavities; The placed cavities resonate at progressively lower RF resonance frequencies to maintain the approximate resonance of the charged particles, and each RF resonance frequency of each of the successively placed cavities corresponds to a difference frequency. A cyclotron resonance accelerator, wherein the pulses of the charged particles are reduced in substantially equal increments and are emitted corresponding to the difference frequency. The cyclotron resonance accelerator according to claim 1, further comprising a coaxial dielectric liner disposed in at least one of the plurality of cavities. The cyclotron resonance accelerator according to claim 1, further comprising a plurality of radial wings disposed in at least one of the plurality of cavities. 4. The cyclotron resonance accelerator of claim 3, wherein said plurality of radial wings further comprises four radiating wings configured to provide a radio frequency double dipole (RFDD). The cyclotron resonance accelerator according to claim 1, wherein the electrically charged particles are selected from the group consisting of ions, electrons, protons, and muons. Each of the plurality of cavities is TE ₁₁₁ The cyclotron resonance accelerator according to claim 1, which resonates in a mode. Radiating the charged particles as pulses from a charged particle source,
Sending said charged particles axially through a plurality of successively arranged rotational mode cavities extending axially;
Providing a substantially uniform magnetic field along an axial extent of the plurality of sequentially arranged cavities;
Operating each successively located cavity at progressively lower RF resonance frequencies to maintain an approximate resonance of the pulse of charged particles, wherein each RF frequency of the successively located cavity is Decreases in substantially equal increments corresponding to the difference frequency, wherein the pulses of the charged particles are emitted in response to the difference frequency. 8. The method of claim 7, wherein emitting a pulse further comprises emitting the pulse of the charged particles at a time interval corresponding to a reciprocal of the difference frequency. The method of claim 7, further comprising the step of capacitively charging at least one of the plurality of cavities. The method of claim 7, wherein the charged particles are selected from the group consisting of ions, electrons, protons, and muons. The actuating step includes the step of making each of the plurality of cavities TE ₁₁₁ The method of claim 7, further comprising resonating in a mode. In a system that accelerates charged particles,
Means for emitting a pulse of the charged particles,
Means for transmitting said charged particles in an axial direction through a plurality of consecutively arranged rotational mode cavities extending in an axial direction;
Means for providing a substantially uniform magnetic field along an axial extent of the plurality of sequentially arranged cavities;
Means for operating each successively located cavity at progressively lower RF frequencies to maintain the approximate resonance of the charged particles, wherein the RF frequency of each of the successively located cavities is different. The system wherein the pulses of the charged particles are reduced in substantially equal increments corresponding to frequency and emitted in response to the difference frequency. Each of the plurality of cavities is TE ₁₁₁ 13. The system of claim 12, wherein the system resonates in a mode. 13. The system of claim 12, further comprising means for reducing a cutoff frequency for a desired dipole mode. 13. The system of claim 12, wherein said charged particles are selected from the group consisting of ions, electrons, protons, and muons. 13. The system of claim 12, further comprising means for controlling an amount of power applied to each of the plurality of sequentially arranged cavities.

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