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Outline

Title
Abstract
Figures
Design Goals
Some Guidelines for Central Region Design
Different Methods of Injection
Some Aspects of Cyclotron Magnetic Design
Design Approach Using OPERA-3D Modelling
Conclusions
References
All Topics
Engineering

Cyclotrons: Magnetic Design and Beam Dynamics

Profile image of Wiel KleevenWiel Kleeven

2017, arXiv: Medical Physics

https://doi.org/10.23730/CYRSP-2017-001.177
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63 pages

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Abstract

Classical, isochronous, and synchro-cyclotrons are introduced. Transverse and longitudinal beam dynamics in these accelerators are covered. The problem of vertical focusing and iscochronism in compact isochronous cyclotrons is treated in some detail. Different methods for isochronization of the cyclotron magnetic field are discussed. The limits of the classical cyclotron are explained. Typical features of the synchro-cyclotron, such as the beam capture problem, stable phase motion, and the extraction problem are discussed. The main design goals for beam injection are explained and special problems related to a central region with an internal ion source are considered. The principle of a Penning ion gauge source is addressed. The issue of vertical focusing in the cyclotron centre is briefly discussed. Several examples of numerical simulations are given. Different methods of (axial) injection are briefly outlined. Different solutions for beam extraction are described. These include th...

Figures (75)
Fig. 1: At first order, a particle in a cyclotron rotates at constant frequency, independent of radius or energy This is illustrated in Fig. 1. Thus, the angular velocity is constant: it is independent of radius, elocity, energy (in the non-relativistic limit), or time.
Fig. 1: At first order, a particle in a cyclotron rotates at constant frequency, independent of radius or energy This is illustrated in Fig. 1. Thus, the angular velocity is constant: it is independent of radius, elocity, energy (in the non-relativistic limit), or time.
Fig. 2: Synchronism in a cyclotron between the particle rotation and the RF accelerating wave (courtesy of Frederic Chautard.) Here mp is the particle rest-mass and c is the speed of light.
Fig. 2: Synchronism in a cyclotron between the particle rotation and the RF accelerating wave (courtesy of Frederic Chautard.) Here mp is the particle rest-mass and c is the speed of light.
Fig. 3: Owing to the relativistic mass increase and the small negative magnetic field gradient, the particle in a classical cyclotron runs steadily out of phase with respect to the RF. Nevertheless, acceleration can be obtained during a limited number of turns (courtesy of Frederic Chautard.)
Fig. 3: Owing to the relativistic mass increase and the small negative magnetic field gradient, the particle in a classical cyclotron runs steadily out of phase with respect to the RF. Nevertheless, acceleration can be obtained during a limited number of turns (courtesy of Frederic Chautard.)
Fig. 4: A simple Excel model can show how much energy can be reached in a weak-focusing rotational symmetric cyclotron, depending on the dee voltage, the field index, and the magnetic field value.
Fig. 4: A simple Excel model can show how much energy can be reached in a weak-focusing rotational symmetric cyclotron, depending on the dee voltage, the field index, and the magnetic field value.
Fig. 5: Some properties of the IBA superconducting synchro-cyclotron (S2C2). Left: modulation of the RF frequency as a function of time within one pulse. Right: average magnetic field and vertical tuning as a function of radius.
Fig. 5: Some properties of the IBA superconducting synchro-cyclotron (S2C2). Left: modulation of the RF frequency as a function of time within one pulse. Right: average magnetic field and vertical tuning as a function of radius.
Fig. 6: Longitudinal beam dynamics in a synchro-cyclotron. Left: flow lines and separatrix in longitudinal phase space. Right: equations of motion that govern this phase space.
Fig. 6: Longitudinal beam dynamics in a synchro-cyclotron. Left: flow lines and separatrix in longitudinal phase space. Right: equations of motion that govern this phase space.
Fig. 7: Magnet of a compact azimuthally varying field cyclotron. Left: the hill sectors and poles, the valleys, and the different parts of the yoke. Right: histogram of the magnetic field.
Fig. 7: Magnet of a compact azimuthally varying field cyclotron. Left: the hill sectors and poles, the valleys, and the different parts of the yoke. Right: histogram of the magnetic field.
Fig. 8: Vertical focusing in an azimuthally varying field cyclotron. Left: scalloping of the orbit with respect to the geometrical circle. Right: the radial velocity component and the azimuthal field component 10 mm above the median plane. The product of these gives the stabilizing vertical Lorentz forces directed towards the median plane.
Fig. 8: Vertical focusing in an azimuthally varying field cyclotron. Left: scalloping of the orbit with respect to the geometrical circle. Right: the radial velocity component and the azimuthal field component 10 mm above the median plane. The product of these gives the stabilizing vertical Lorentz forces directed towards the median plane.
Fig. 9: Vertical focusing in a cyclotron relates closely to vertical focusing at the entrance and exit of a dipole magnet.
Fig. 9: Vertical focusing in a cyclotron relates closely to vertical focusing at the entrance and exit of a dipole magnet.
Fig. 10: Vertical focusing in an azimuthally varying field cyclotron can be strongly increased by spiralling the hill sectors.
Fig. 10: Vertical focusing in an azimuthally varying field cyclotron can be strongly increased by spiralling the hill sectors.
Fig. 11: Simple model to estimate flutter in a hard-edge approximation where A,, and B,, are the normalized Fourier harmonics of the field. With this representation of the field, the flutter can be written as
Fig. 11: Simple model to estimate flutter in a hard-edge approximation where A,, and B,, are the normalized Fourier harmonics of the field. With this representation of the field, the flutter can be written as
Fig. 12: Spiral angle € of the pole
Fig. 12: Spiral angle € of the pole
Fig. 13: The most important cyclotron vendors or manufacturers. RP, radiopharmaceuticals (mostly isotope pro- duction); PT, proton therapy.
Fig. 13: The most important cyclotron vendors or manufacturers. RP, radiopharmaceuticals (mostly isotope pro- duction); PT, proton therapy.
Fig. 14: Deep-valley cyclotron; the concept is used in many compact isotope production and proton therapy Papers
Fig. 14: Deep-valley cyclotron; the concept is used in many compact isotope production and proton therapy Papers
Fig. 16: Mapping system carrying a Hall probe that moves on a polar grid in the cyclotron median plane
Fig. 16: Mapping system carrying a Hall probe that moves on a polar grid in the cyclotron median plane
Fig. 17: Upper left: isochronization of a cyclotron magnetic field is achieved by machining the profile of a remov- able pole edge. Lower left: a rough estimate of the shimming effect (change of the average magnetic field) can be obtained with a hard-edge model. Right: a better prediction of the shimming can be obtained by calculating (with a 3D finite-element code) the change of the radial profile of the average magnetic field due to a well-defined pole cut and repeating this for several cuts at varying radii. Fig. 17: Upper left: isochronization of a cyclotron magnetic field is achieved by machining the profile of a remov-
Fig. 17: Upper left: isochronization of a cyclotron magnetic field is achieved by machining the profile of a remov- able pole edge. Lower left: a rough estimate of the shimming effect (change of the average magnetic field) can be obtained with a hard-edge model. Right: a better prediction of the shimming can be obtained by calculating (with a 3D finite-element code) the change of the radial profile of the average magnetic field due to a well-defined pole cut and repeating this for several cuts at varying radii. Fig. 17: Upper left: isochronization of a cyclotron magnetic field is achieved by machining the profile of a remov-
Fig. 18: Left: IBA C235 cyclotron for proton therapy. Right: in this cyclotron there are three removable pole edges for isochronization of the magnetic field.
Fig. 18: Left: IBA C235 cyclotron for proton therapy. Right: in this cyclotron there are three removable pole edges for isochronization of the magnetic field.
Fig. 19: Left: upper poles of the IBA C18/9 cyclotron. The movable iron wedges (flaps) are used to change the average magnetic field profile from protons (flaps close to the median plane) to deuterons (flaps farther away from the median plane). Right: relativistic correction of the magnetic field, as needed for protons (about 2.1%) and for deuterons (about 0.53%).
Fig. 19: Left: upper poles of the IBA C18/9 cyclotron. The movable iron wedges (flaps) are used to change the average magnetic field profile from protons (flaps close to the median plane) to deuterons (flaps farther away from the median plane). Right: relativistic correction of the magnetic field, as needed for protons (about 2.1%) and for deuterons (about 0.53%).
Fig. 20: Finite-element Opera-3d simulation of the effect of the flaps in the IBA C18/9 cyclotron. Left: the neutron field with the flaps farther away from the median plane. Right: the proton field with the flaps close to the median plane.
Fig. 20: Finite-element Opera-3d simulation of the effect of the flaps in the IBA C18/9 cyclotron. Left: the neutron field with the flaps farther away from the median plane. Right: the proton field with the flaps close to the median plane.
Fig. 21: Alternative method for isochronization of a dual-particle cyclotron. In this case, the flaps are in a fixed position and connected magnetically to the base of the return yoke by a solid iron cylinder. The magnetic flux into the flaps is controlled by the solenoidal coil around the cylinder. This method has not yet been realized but has been patented by IBA.
Fig. 21: Alternative method for isochronization of a dual-particle cyclotron. In this case, the flaps are in a fixed position and connected magnetically to the base of the return yoke by a solid iron cylinder. The magnetic flux into the flaps is controlled by the solenoidal coil around the cylinder. This method has not yet been realized but has been patented by IBA.
Fig. 22: Yet another method for isochronization of a dual-particle cyclotron is to split the pole into three layers and to wind coils around the middle layers. As explained in the right figure, these coils push magnetic field from the outer pole region towards the centre or vice versa, depending on the polarity of the coil current. Note that in the upper left figure, the cover has been removed.
Fig. 22: Yet another method for isochronization of a dual-particle cyclotron is to split the pole into three layers and to wind coils around the middle layers. As explained in the right figure, these coils push magnetic field from the outer pole region towards the centre or vice versa, depending on the polarity of the coil current. Note that in the upper left figure, the cover has been removed.
Fig. 23: A method similar to the one outlined in Fig. 22 is used in the AGOR superconducting cyclotron [20, 21.
Fig. 23: A method similar to the one outlined in Fig. 22 is used in the AGOR superconducting cyclotron [20, 21.
Fig. 24: A more general method is used to isochronize multiparticle variable-energy cyclotrons. Here, an array of concentric circular coils is placed on the pole and each coil uses its own independent power supply. In this way, there is a lot of flexibility in creating the required average magnetic field profile. Left: correction coils for the Berkeley 88-inch cyclotron [24]. Right: correction coils of the Philips 30 MeV azimuthally varying field cyclotron [23].
Fig. 24: A more general method is used to isochronize multiparticle variable-energy cyclotrons. Here, an array of concentric circular coils is placed on the pole and each coil uses its own independent power supply. In this way, there is a lot of flexibility in creating the required average magnetic field profile. Left: correction coils for the Berkeley 88-inch cyclotron [24]. Right: correction coils of the Philips 30 MeV azimuthally varying field cyclotron [23].
Fig. 25: Left: the IBA C70 as an example of an industrial cyclotron for medical isotope production, showing the small spiral in the pole to adjust vertical focusing and the removable pole edge for isochronization. Right: average magnetic field and flutter of this cyclotron. ‘ig. 25: Left: the IBA C70 as an example of an industrial cyclotron for medical isotope production, showing the
Fig. 25: Left: the IBA C70 as an example of an industrial cyclotron for medical isotope production, showing the small spiral in the pole to adjust vertical focusing and the removable pole edge for isochronization. Right: average magnetic field and flutter of this cyclotron. ‘ig. 25: Left: the IBA C70 as an example of an industrial cyclotron for medical isotope production, showing the
Fig. 26: Left: RF phase slip per turn and integrated RF phase slip in the IBA C70 cyclotron. Right: calculated phase slip per turn can be related to the required shimming of the removable pole edges.
Fig. 26: Left: RF phase slip per turn and integrated RF phase slip in the IBA C70 cyclotron. Right: calculated phase slip per turn can be related to the required shimming of the removable pole edges.
Fig. 27: Left: radial (v,.) and vertical (v,) tune function of the IBA C70 cyclotron as a function of radius. Right: related tuning diagram, showing the working curve and some important resonance lines.
Fig. 27: Left: radial (v,.) and vertical (v,) tune function of the IBA C70 cyclotron as a function of radius. Right: related tuning diagram, showing the working curve and some important resonance lines.
Fig. 29: Stability diagram of a cyclotron with three-fold rotational symmetry, assuming that the flutter is relatively small, as it is produced by the iron poles. The solid black line shows the maximum kinetic energy (relativistic +) that can be obtained, taking into account the requirements of vertical focusing, as well as the 2v,. = 3 stop band.
Fig. 29: Stability diagram of a cyclotron with three-fold rotational symmetry, assuming that the flutter is relatively small, as it is produced by the iron poles. The solid black line shows the maximum kinetic energy (relativistic +) that can be obtained, taking into account the requirements of vertical focusing, as well as the 2v,. = 3 stop band.
Fig. 30: Left: in a cyclotron, the radial betatron oscillation can be represented as a (slow) motion of the orbit centre. Right: the betatron oscillations take place with respect to the magnetic centre of the cyclotron. Owing to a first-harmonic field error, the magnetic centre shifts away from the geometric centre of the cyclotron. Fig. 30: Left: in a cyclotron, the radial betatron oscillation can be represented as a (slow) motion of the orbit
Fig. 30: Left: in a cyclotron, the radial betatron oscillation can be represented as a (slow) motion of the orbit centre. Right: the betatron oscillations take place with respect to the magnetic centre of the cyclotron. Owing to a first-harmonic field error, the magnetic centre shifts away from the geometric centre of the cyclotron. Fig. 30: Left: in a cyclotron, the radial betatron oscillation can be represented as a (slow) motion of the orbit
Fig. 31: Amplitudes of the (most important) harmonic field errors in the measured field map of the IBA C70 cyclotron.
Fig. 31: Amplitudes of the (most important) harmonic field errors in the measured field map of the IBA C70 cyclotron.
Fig. 32: Left: Monarch S250 synchro-cyclotron from Mevion (Couresy Mevion medical systems Ref. [26]). Right: superconducting synchro-cyclotron (S2C2) from IBA.
Fig. 32: Left: Monarch S250 synchro-cyclotron from Mevion (Couresy Mevion medical systems Ref. [26]). Right: superconducting synchro-cyclotron (S2C2) from IBA.
Fig. 33: Mismatch between the cyclotron eigenellipse and the beam ellipse injected into the machine leads, after many ture ton an increace af the circulating emittance
Fig. 33: Mismatch between the cyclotron eigenellipse and the beam ellipse injected into the machine leads, after many ture ton an increace af the circulating emittance
Fig. 34: Left: cold-cathode Penning ion gauge source. Right: two chimneys, two cathodes, and a puller. The chimney on the right shows an eroded slit.
Fig. 34: Left: cold-cathode Penning ion gauge source. Right: two chimneys, two cathodes, and a puller. The chimney on the right shows an eroded slit.
Fig. 35: Central region of the IBA C18/9 cyclotron showing the dees and dummy dees. One of the two ion sources has been removed to show the puller. The figure also shows the four hill sectors. The removable circular disc underneath the central region is the central plug; it is used to fine tune the magnetic field bump in the centre.
Fig. 35: Central region of the IBA C18/9 cyclotron showing the dees and dummy dees. One of the two ion sources has been removed to show the puller. The figure also shows the four hill sectors. The removable circular disc underneath the central region is the central plug; it is used to fine tune the magnetic field bump in the centre.
Fig. 36: Example of a 3D finite-element model of the IBA C18/9 central region. Fine meshing is used in regions with small geometrical details, such as the source—puller gap. The graded mesh size allows modelling of the full dee-structure. Complete parameterization of the model is used for fast modification and optimization.
Fig. 36: Example of a 3D finite-element model of the IBA C18/9 central region. Fine meshing is used in regions with small geometrical details, such as the source—puller gap. The graded mesh size allows modelling of the full dee-structure. Complete parameterization of the model is used for fast modification and optimization.
Fig. 37: Calculated orbits in the IBA C18/9 central region. The D™ source is shifted farther outward because its orbit is larger. Note that parts of the D™ chimney have been cut away, to give sufficient clearance for the H~ beam. Assessment of longitudinal matching is illustrated: the red dots and the green dots give the particle position when the dee voltage is zero and a maximum, respectively. Ideally, the red dots should be on the dee centre line. Electric fields are obtained from Opera. Magnetic fields from Opera or from a measured map.
Fig. 37: Calculated orbits in the IBA C18/9 central region. The D™ source is shifted farther outward because its orbit is larger. Note that parts of the D™ chimney have been cut away, to give sufficient clearance for the H~ beam. Assessment of longitudinal matching is illustrated: the red dots and the green dots give the particle position when the dee voltage is zero and a maximum, respectively. Ideally, the red dots should be on the dee centre line. Electric fields are obtained from Opera. Magnetic fields from Opera or from a measured map.
Fig. 38: Energy gain per turn depends on several parameters, such as the dee voltage Vace, the number of dees, NV, the harmonic mode, h, the dee angle, a, and the RF phase ®pp. For a dee angle of 45°, the harmonic mode h = 4 is most efficient. Fig. 38: Energy gain per turn depends on several parameters, such as the dee voltage Vace, the number of dees, N,
Fig. 38: Energy gain per turn depends on several parameters, such as the dee voltage Vace, the number of dees, NV, the harmonic mode, h, the dee angle, a, and the RF phase ®pp. For a dee angle of 45°, the harmonic mode h = 4 is most efficient. Fig. 38: Energy gain per turn depends on several parameters, such as the dee voltage Vace, the number of dees, N,
Fig. 39: Vertical electrical focusing in the cyclotron accelerating gap. This focusing is important only in th cyclotron centre.
Fig. 39: Vertical electrical focusing in the cyclotron accelerating gap. This focusing is important only in th cyclotron centre.
Fig. 40: Normalized vertical electrical forces obtained from orbit tracking of a particle during five turns in a central region with two dees (four accelerating gaps). Dee crossings are indicated at the top of the curve (in blue) and gap crossings (two per dee) at the bottom of the curve (in green). Each gap is focusing at the entrance and defocusing at the exit.
Fig. 40: Normalized vertical electrical forces obtained from orbit tracking of a particle during five turns in a central region with two dees (four accelerating gaps). Dee crossings are indicated at the top of the curve (in blue) and gap crossings (two per dee) at the bottom of the curve (in green). Each gap is focusing at the entrance and defocusing at the exit.
Fig. 41: Left: calculated orbits in the central region of the IBA S2C2. Right: 3D view of the Penning ion gauge source and puller used in this central region.
Fig. 41: Left: calculated orbits in the central region of the IBA S2C2. Right: 3D view of the Penning ion gauge source and puller used in this central region.
Fig. 42: The ion source and central region can be extracted from the cyclotron as one assembly, for easy mainten- ance and precise repositioning.
Fig. 42: The ion source and central region can be extracted from the cyclotron as one assembly, for easy mainten- ance and precise repositioning.
Fig. 43: Simulation of the beam capture process in the S2C2 central region (CR).
Fig. 43: Simulation of the beam capture process in the S2C2 central region (CR).
Fig. 44: Small bits of thin paper are placed in the pole gap and burned by the beam, to find the beam position and size during the first few turns.
Fig. 44: Small bits of thin paper are placed in the pole gap and burned by the beam, to find the beam position and size during the first few turns.
Fig. 45: Horizontal (trochoidal) injection. The beam travels along the hill—valley pole edge. In the centre, an electrostatic device places the beam on the equilibrium orbit. Figure taken from Ref. [28]
Fig. 45: Horizontal (trochoidal) injection. The beam travels along the hill—valley pole edge. In the centre, an electrostatic device places the beam on the equilibrium orbit. Figure taken from Ref. [28]
Fig. 46: Left: mirror inflector. Right: hyperboloid inflector. Figure taken from Ref. [28]
Fig. 46: Left: mirror inflector. Right: hyperboloid inflector. Figure taken from Ref. [28]
Fig. 47: 1:1 model of the spiral inflector and central region of the IBA Cyclone 30 cyclotron
Fig. 47: 1:1 model of the spiral inflector and central region of the IBA Cyclone 30 cyclotron
Fig. 48: Left: axially injected 3D orbits calculated with the cyclotron tracking code AOC are imported in the
Fig. 48: Left: axially injected 3D orbits calculated with the cyclotron tracking code AOC are imported in the
Fig. 49: C30HC injection line installed on top of the cyclotron. The ion source is on top of the vacuum box. This box is pumped by two turbo pumps (front and back).
Fig. 49: C30HC injection line installed on top of the cyclotron. The ion source is on top of the vacuum box. This box is pumped by two turbo pumps (front and back).
Fig. 50: Left: layout of the C30HC injection line. Right: beam envelopes in this beam line, calculated with TRANSPORT.
Fig. 50: Left: layout of the C30HC injection line. Right: beam envelopes in this beam line, calculated with TRANSPORT.
Fig. 51: Left: IBA C18+ cyclotron with an internal rhodium target for the production of palladium. Right: detail of an internal target showing the profiling of the target surface, optimized to maximize the beam spot and minimize beam reflection on the target. Fig. 51: Left: IBA C18+ cyclotron with an internal rhodium target for the production of palladium. Right: detail
Fig. 51: Left: IBA C18+ cyclotron with an internal rhodium target for the production of palladium. Right: detail of an internal target showing the profiling of the target surface, optimized to maximize the beam spot and minimize beam reflection on the target. Fig. 51: Left: IBA C18+ cyclotron with an internal rhodium target for the production of palladium. Right: detail
Fig. 52: Left: H™ extraction by stripping. Energy is selected by moving the stripper foil to the correct radius. Right: a simple carbon stripper foil is used to extract the beam (typically 50-200 ug/cm?).
Fig. 52: Left: H™ extraction by stripping. Energy is selected by moving the stripper foil to the correct radius. Right: a simple carbon stripper foil is used to extract the beam (typically 50-200 ug/cm?).
Fig. 53: Left: H™ extraction by stripping. Several targets can be placed around the machine. Right: median plane of a typical IBA isotope production cyclotron, showing the most important subsystems.
Fig. 53: Left: H™ extraction by stripping. Several targets can be placed around the machine. Right: median plane of a typical IBA isotope production cyclotron, showing the most important subsystems.
Fig. 54: Mechanisms that may contribute to an increase of the turn separation in a cyclotron
Fig. 54: Mechanisms that may contribute to an increase of the turn separation in a cyclotron
Fig. 55: Harmonic coil used in the IBA self-extracting cyclotron (note that the ruler measures centimeters)
Fig. 55: Harmonic coil used in the IBA self-extracting cyclotron (note that the ruler measures centimeters)
Fig. 56: Top: principle function of an electrostatic deflector. Bottom: electrostatic deflector installed in the IBA C235 cyclotron.
Fig. 56: Top: principle function of an electrostatic deflector. Bottom: electrostatic deflector installed in the IBA C235 cyclotron.
Fig. 57: Close-up of C235 ESD, showing the septum and the electrode
Fig. 57: Close-up of C235 ESD, showing the septum and the electrode
Fig. 58: Left: vertical cross-section of the passive gradient corrector channel used in the small ILEC cyclotron at Technical University Eindhoven. Right: calculated magnetic field and field gradient. The field is increasing with radius, increasing the radial focusing. Figure taken from Ref. [49]
Fig. 58: Left: vertical cross-section of the passive gradient corrector channel used in the small ILEC cyclotron at Technical University Eindhoven. Right: calculated magnetic field and field gradient. The field is increasing with radius, increasing the radial focusing. Figure taken from Ref. [49]
Fig. 59: Extraction scheme used for the IBA C235 proton therapy cyclotron
Fig. 59: Extraction scheme used for the IBA C235 proton therapy cyclotron
Fig. 60: Left: definition of the elliptical pole gap used in the IBA C235 cyclotron. Right: the magnetic field shows a very sharp cut-off near the radius of the pole.
Fig. 60: Left: definition of the elliptical pole gap used in the IBA C235 cyclotron. Right: the magnetic field shows a very sharp cut-off near the radius of the pole.
Fig. 61: Left: gradient corrector installed in the C235 cyclotron. Right: magnetic field at two different azimuths, showing the field profile experienced by the extracted beam.
Fig. 61: Left: gradient corrector installed in the C235 cyclotron. Right: magnetic field at two different azimuths, showing the field profile experienced by the extracted beam.
Fig. 62: Left: permanent magnet quadrupole doublet, installed in the IBA C235 cyclotron. Right: layout and polarity of the permanent magnet, producing the high-quality quadrupole field.
Fig. 62: Left: permanent magnet quadrupole doublet, installed in the IBA C235 cyclotron. Right: layout and polarity of the permanent magnet, producing the high-quality quadrupole field.
Fig. 63: In the IBA self-extracting cyclotron, a groove is machined in one of the poles (right), to create an extraction channel. This channel provides a magnetic septum at the entrance and, at the same time, gradient correction and focusing. An elliptical pole gap is used, allowing for sharp radial gradients in the magnetic field near the pole edge. near the pole edge.
Fig. 63: In the IBA self-extracting cyclotron, a groove is machined in one of the poles (right), to create an extraction channel. This channel provides a magnetic septum at the entrance and, at the same time, gradient correction and focusing. An elliptical pole gap is used, allowing for sharp radial gradients in the magnetic field near the pole edge. near the pole edge.
Fig. 64: Left: extraction elements in the IBA self-extracting cyclotron. The harmonic coils are placed underneath the pole covers. Right: lower part of the permanent magnet corrector used in the IBA self-extracting cyclotron. The corrector is placed close to the vacuum chamber visible in the lower part of the photo. The polarity of the magnets is indicated. The polarities are inverted in the upper part of the corrector.
Fig. 64: Left: extraction elements in the IBA self-extracting cyclotron. The harmonic coils are placed underneath the pole covers. Right: lower part of the permanent magnet corrector used in the IBA self-extracting cyclotron. The corrector is placed close to the vacuum chamber visible in the lower part of the photo. The polarity of the magnets is indicated. The polarities are inverted in the upper part of the corrector.
Fig. 65: Dual extraction system (stripping and electrostatic deflector) used in the IBA C70XP-cyclotron: PMQ, permanent magnet quadrupole.
Fig. 65: Dual extraction system (stripping and electrostatic deflector) used in the IBA C70XP-cyclotron: PMQ, permanent magnet quadrupole.
Fig. 66: High-power electrostatic deflector used in the IBA C70XP-cyclotron
Fig. 66: High-power electrostatic deflector used in the IBA C70XP-cyclotron
Fig. 67: C400 superconducting cyclotron and main parameters, proposed by IBA for carbon and proton therapy: SC, superconducting.
Fig. 67: C400 superconducting cyclotron and main parameters, proposed by IBA for carbon and proton therapy: SC, superconducting.
Fig. 68: Left: in the IBA C400 cyclotron, protons are extracted by stripping the accelerated Hy ion by a thin stripping foil. Right: !2C°* is extracted with an electrostatic deflector. Both particles, protons and carbon, are combined into one beam line.
Fig. 68: Left: in the IBA C400 cyclotron, protons are extracted by stripping the accelerated Hy ion by a thin stripping foil. Right: !2C°* is extracted with an electrostatic deflector. Both particles, protons and carbon, are combined into one beam line.
Fig. 69: Passive extraction system of the IBA superconducting synchro-cyclotron S2C2: PMQ, permanent magnet quadrupole.
Fig. 69: Passive extraction system of the IBA superconducting synchro-cyclotron S2C2: PMQ, permanent magnet quadrupole.
Fig. 70: Regenerative extraction: a strong quadrupole bump increases v,. and locks it to one. A steady shift of the beam towards the extraction channel is built up. The Walkinshaw resonance (v, = 2) must be avoided. Fig. 70: Regenerative extraction: a strong quadrupole bump increases 1, and locks it to one. A steady shift of the
Fig. 70: Regenerative extraction: a strong quadrupole bump increases v,. and locks it to one. A steady shift of the beam towards the extraction channel is built up. The Walkinshaw resonance (v, = 2) must be avoided. Fig. 70: Regenerative extraction: a strong quadrupole bump increases 1, and locks it to one. A steady shift of the
Fig. 71: Logical structure of a typical input file used for the fully parameterized and automated creation of an Opera-3d model of a cyclotron.
Fig. 71: Logical structure of a typical input file used for the fully parameterized and automated creation of an Opera-3d model of a cyclotron.
Fig. 72: The Opera-2d model of the S2C2
Fig. 72: The Opera-2d model of the S2C2
Fig. 73: Opera-2d simulation of the median plane error in the S2C2, as produced by the feet underneath the cyclotron, and compensation by an iron ring placed on top of the yoke.
Fig. 73: Opera-2d simulation of the median plane error in the S2C2, as produced by the feet underneath the cyclotron, and compensation by an iron ring placed on top of the yoke.
Fig. 74: Opera-3d preprocessor model of the S2C2, to estimate forces and torques due to displacement acting on the cold mass with respect to the geometrical centre of the cyclotron.
Fig. 74: Opera-3d preprocessor model of the S2C2, to estimate forces and torques due to displacement acting on the cold mass with respect to the geometrical centre of the cyclotron.
Fig. 75: A complete and detailed Opera-3D model was made of the IBA S2C2
Fig. 75: A complete and detailed Opera-3D model was made of the IBA S2C2

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DC280 is novel cyclotron which is created i the FLNR JINR. This cyclotron allows accelerating the ions of elements from Helium to Uranium with the mass to charge ratio in the range of 4 – 7.5 providing ion currents up to 10 pμA. The simulation of ion beam dynamics in the high voltage axial injection beam line of DC280 cyclotron is presented. One part of the injection system is placed at the High Voltage Platform and other part is in the grounded yoke of the DC-280 magnet. The 3D electromagnetic field maps of the focusing solenoids, analyzing magnet, accelerating tube and spherical electrostatic deflector are used during this simulation. The calculated efficiency of ion beam transportation is equal to 100%.

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Vacuum System of the Ion Source and Injection Line of a High Current Compact Cyclotron
Chinmay Nandi

Journal of Physics: Conference Series, 2012

A 2.45 GHz microwave ion source and the transport system of high current proton beam for injection study in a compact cyclotron have been designed, fabricated indigenously, installed and commissioned. Presently it is under testing for beam characterization and inflection study. The vacuum system consists of a plasma chamber with 8mm slit in the plasma electrode, two-segment ceramic insulators (Al2O3) column, which supports the beam extraction electrodes and isolates the high voltage deck from the beam line and a 3m long low energy beam transport line (LEBT) equipped with several diagnostic elements such as faraday cup, slits, beam viewer etc. There is a provision to connect a needle valve to feed gas into the chamber for beam space charge neutralization studies. An online vacuum data logging software has been developed for continuous monitoring of the vacuum near the extraction zone. Monitoring system being very sensitive to the high voltage breakdown, is designed with a spark protection circuit which provides an isolation of 10kV using an optical isolation technique. In this paper we present design philosophy, operating experience and some experimental results. We have studied the behaviour of vacuum system near the extraction zone under various operating conditions of the high current ion source.

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Development of an injection system for a compact H- cyclotron, the concomitant measurement of injected beam properties and the experimental characterization of the spiral inflector
Morgan Dehnel

1995

This thesis addresses two major problems. One is of interest to commercial cyclotron manufacturers and the other is of interest to the accelerator physics community. The industrial problem was to produce a compact and modular ion source and injection system for the new TR13 H~ cyclotron, which is capable of transporting and injecting a high quality and well matched beam into the cyclotron. The accelerator physics problem was to advance the science of inflector ion optical design, analysis and troubleshooting from the realm of pure simulation to the realm of measurement and experimentation. The industrial problem was solved by designing candidate injection systems in parallel with the TR13 cyclotron design. These systems were fabricated and then experimentally optimized along with the ion source on a 1 MeV test cyclotron. This work resulted in a set of ion source and injection systems with well documented and understood properties. The recommended solution for the TR13 was a cost eff...

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The Results of Magnetic Field Formation and Commissioning of Heavy-Ion Isochronous Cyclotron DC280
Ivan Ivanenko

2020

The DC280 cyclotron is the new accelerator of FLNR Super Heavy Elements Factory. It was commissioned in the beginning of 2019. DC280 is intended for production of high intensity, up to 10 pmkA, beams of heavy ions with mass to charge ratio A/Z= 4 - 7. The wide range of accelerated ions from helium to uranium and smooth variation of extracted beam energy in the range W= 4 - 8 MeV/n are provided by varying of level of main magnetic field from 0.64 T till 1.32 T. The DC280 magnetic field was formed in a good conformity with results of computer modeling. In spite of commissioning of cyclotron still is in progress, the first experiments gave the intensity 1.35 pmkA of 84Kr¹⁴⁺ and 10 pmkA of 12C²⁺. At the present work the results of calculations, magnetic field measurements and first experiments are presented.

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A Separated-Sector Cyclotron Post-Accelerator for the Oak Ridge Heavy Ion Laboratory
Karla Fischer

EXS, 1975

A separated sector cyclotron post-accelerator , is proposed for the Oak Ridge Heavy Ion Laboratory. The SSC accepts beams from either ORIC or the 25 MV tandem electrostatic accelerator and extends the maximum particle energy to 75 MeV/u for A less than 40 and to at least 10 MeV/u for A greater than 40. The SSC has a field-radius product of 2540 kG-cm, a 4-sector configuration, and azimuthal pole width of 52°. RF acceleration of up to 1 MV per turn is obtained with two resonators in opposite valleys. An RF tuning range of 6 to 14 MHz accommodates acceleration on harmonics 2 through 11. Concentric second harmonic resonators are provided for optimizing phase acceptance.

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A study for design of the new N = 1 central region of the Princeton University AVF cyclotron
Moohyun Yoon

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1988

As part of the long-term upgrading project of the Princeton University AVF cyclotron, we have carried out design studies of the axial injection system and the accompanying new central regions for the cyclotron. Such studies were required by the desire to accelerate high charge-state ions as well as polarized ions in the cyclotron. At present, an internal PIG source provides beams of various charge states. The design studies of this new system were carried out on the basis of detailed beam orbit dynamics investigations. In this paper, we present studies for the existing central region for the first-harmonic (N = 1) mode of acceleration and design procedures of the new central region.

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Characteristics of Beam Extraction System of K500 Superconducting Cyclotron
Malay Dey

Extensive Magnetic Field measurement of the K500 Superconducting Cyclotron has been completed. In this paper we report the beam dynamical calculations along the extraction system based on the measured magnetic field data. The beam matching to the external beam transport system, for different ion species spanning the operating region is also explored.

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Design of the central region for axial injection in the VINCY cyclotron
Dragan Toprek

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1996

This paper describes the design of the central region for h=l, h=2 and h=4 modes of acceleration in the VINCY Cyclotron. The central region is unique and compatible with the three above mentioned harmonic modes of operation. Only one inflector of the spiral type will be used. The central region is designed to operate with two external ion sources: (a) an ECR ion source of the maximum extraction voltage of 25 kV-for heavy ions, and (b) a multicusp ion source of the maximum extraction voltage of 30 kV-for Hand D' ions. Heavy ions will be accelerated by the second and fourth harmonics, D-ions by the second harmonic and H-ions by the first harmonic of the RF field. The central region is equipped with an axial injection system. The electric field distribution in the four acceleration gaps has been numerically calculatied by the computer code RELAX3D. The geometry of the central region has been tested with the orbit computations carried out by means of the code CYCLONE The properties of the beam in the spiral inflector were studied by using the code CASINO.

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