Institutional Repository of Institute of Modern Physics, CAS
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A DESIGN OF SWITCH MAGNET POWER SUPPLY
No full textThe paper introduces a design of power supply for<br />switch magnet in HIRFL. The main circuit topology used<br />Buck chopper regulator, full-bridge inverter output and<br />power units in parallel in the power supply is introduced.<br />The operation principle and control strategy is analyzed<br />in this article. The power supply can be operated in DC<br />and pulse mode, has the very good output current<br />long-term stability, high reliability and dynamic response<br />characteristics. Finally, some experimental data and<br />waveforms of the power supply are shown to<br />demonstrate the performance of the design
INTENSE BEAM OPERATION OF THE NSCL/MSU CYCLOTRONS*
No full textIntense heavy-ion beam acceleration by<br />superconducting compact cyclotrons presents significant<br />challenges since surfaces impacted by lost beam are<br />subject to high thermal loads and consequent damage.<br />High transmission efficiencies allow 0.7 – 1.0 kW beams<br />to be routinely delivered for experiment at the NSCL,<br />with minimal negative impact on reliability. Net beam<br />transmission measured from just before the K500 to<br />extracted beam from the K1200 is often about 30% and<br />usually above 20% depending on the ion used (factoring<br />out the unavoidable loss due to the charge stripping foil in<br />the K1200). Results, techniques and examples are<br />discussed
MAGNETIC FIELD CALCULATION AND MAGNET SHIMMING SIMULATION FOR CYCHU-10 CYCLOTRON
No full textThe compact internal ion source cyclotron CYCHU-10<br />developed in Huazhong University of Science and<br />Technology (HUST) is in magnet machining, and will be<br />assembled soon later. The accuracy of the finite element<br />analysis (FEA) prediction of the magnetic field compared<br />to the measurement is an important guarantee for virtual<br />magnet shimming. In this paper, a further study on<br />magnet field computation using FEA is implemented.<br />Both An 1/8 and a 1/4 models are established to make a<br />comparison. Based on the computation, researches on<br />virtual magnet shimming are also carried out. A new shim<br />tool using an improved matrix method combining the<br />multiple linear regressions is employed to simulate the<br />virtual shimming process. With the aid of 3D finite<br />element code and beam dynamics code, an iterative<br />shimming process has been accomplished successfully.<br />The results verify the feasibility and effectiveness of the<br />shimming method
DESIGN OF RF SYSTEM FOR COMPACT AVF CYCLOTRON*
No full textRF system is one of the most important parts for<br />producing good and efficient accelerator system. The ion<br />beam will be derived by a K100 SSC (Separated-Sector-<br />Cyclotron). 8 MeV SF(Sector-focused) Cyclotron which<br />produces 8 MeV proton beam is used as injector of K100<br />SSC cyclotron. In this paper, we designed RF system<br />including RF cavity. The total specification of system is<br />on the following. The frequency of this RF system is 70<br />MHz coaxial type cavity. Also we applied 4th harmonic,<br />dee voltage of 50KV. We simulated the RF system using<br />commercially available simulator, CST Microwave studioIMP;Chinese Academy of Science
COMMISSIONING EXPERIENCE OF THE RF SYSTEM OF K500 SUPERCONDUCTING CYCLOTRON AT VECC
No full textRadio frequency system of Superconducting cyclotron<br />at VECC, Kolkata, has been developed to achieve<br />accelerating voltage of 100 kV max. With frequency,<br />amplitude and phase stability of 0.1 ppm, 100 ppm and<br />±0.5o respectively in the frequency range of 9 – 27 MHz.<br />Each of the three half-wave coaxial cavity is fed with rf<br />power (80kW max.) from each of the three high power<br />final rf amplifiers based on Eimac 4CW150,000E tetrodes.<br />Initially, the whole three-phase RF system has been tuned<br />for operation with RF power to the cavities at 19.1994<br />MHz and thereafter commissioned the cyclotron with<br />neon 3+ beam at external radius at 14.0 MHz. In this<br />paper, we present brief description of the rf system and<br />behaviour observed during initial conditioning of the<br />cavities with rf power and the way to get out of<br />multipacting zone together with discussion on our<br />operational experience. We have so far achieved dee<br />voltage up to 57 kV at 14 MHz with 20 kW of RF power<br />fed at each of the three dees and achieved vacuum level of<br />4.5 x 10-7 mbar inside the beam chamber. We also present<br />discussion on the problems and failures of some RF<br />components during commissioning stage and<br />rectifications done to solve the same.IMP;Chinese Academy of Science
DESIGN, CONSTRUCTION AND COMMISSIONING OF THE 100KW RF AMPLIFIER FOR CYCIAE-100
No full textAs a major part of the BRIF project, CYCIAE-100, the<br />100MeV high intensity cyclotron being constructed at<br />CIAE, will provide 200μA-500μA proton beam ranging<br />from 75MeV to 100MeV for RIB production. Two<br />identical 100kW RF amplifiers will be used to drive two<br />cavities independently to accelerate H- beam up to 100<br />MeV. The detail technical specification has been<br />investigated, fixed, and initial design has been finished by<br />CIAE. Then, the construction design and manufacture is<br />done by China Academy of Aero and Space. The on site<br />test is successful by mutual efforts. The final<br />commissioning is under way with a full scale prototype<br />cavity at CIAE. A general description of the CYCIAE-100<br />RF system design will be given, as well as the review of<br />100kW amplifier design. In the commissioning of the<br />amplifier with dummy load, different high order<br />resonances are found when operated at different<br />frequencies between 42MHz to 46MHz. An equivalent<br />circuit model is carried out to hunt down the problems.<br />The model and related analysis will be reported together<br />with the process and results of high power test with the<br />cavity load through about 35-meter 6-1/8” rigid coaxial<br />line.IMP;Chinese Academy of Science
OPERATIONAL EXPERIENCE OF SUPERCONDUCTING CYCLOTRON MAGNET AT VECC, KOLKATA
No full textThe Kolkata Superconducting cyclotron magnet has
been operational in the Centre since last few years and
enabled us to extensively map magnetic fields over a
year covering the operating range of the machine and
successful commissioning of internal beam. The magnet
cryostat coupled with the liquid helium refrigerator
performs satisfactorily with moderate currents (<550A)
in both the coils. The superconducting coil did not
undergo any training and over the years has not suffered
from any quench. Author would share the experience
and difficulties of enhanced overall heat load to the
liquid helium refrigerator at higher excitations of coils.
This creates instability in the operation of liquid helium
refrigerator and finally leads to slow dump. Rigorous
study has been carried out in this regard to understand
the problems and operational logic of liquid helium
refrigerator has been modified accordingly to alleviate
from. Some other measures have also been taken from
cryostat and cryogenic distribution point of view in
order to reduce the heat load at higher excitations,
optimize the current lead flow, etc.IMP;Chinese Academy of Science
PROGRESS IN FORMATION OF SINGLE-PULSE BEAMS BY A CHOPPING SYSTEM AT THE JAEA/TIARA FACILITY
No full textThe intervals of beam pulses from a cyclotron are
generally tens of ns and they are too short for pulse
radiolysis experiments which require beam pulses at
intervals over 1 μs (single-pulse beam). A chopping
system, consisting of two types of high voltage kickers, is
used at the JAEA AVF cyclotron to form single-pulse
beam. However, we could not provide single-pulse beam
stably over 30 min since the magnetic field of the
cyclotron gradually decreased and the number of multiturn
extraction increased. The magnetic field is stabilized
at present by keeping temperature of the cyclotron magnet
constant. In addition, a new technique to measure and
control an acceleration beam phase has enabled us to
reduce the number of multi-turn extraction easier than
before. The single-pulse beam of a 320 MeV 12C6+ is
successfully provided without retuning of the cyclotron
over 4 h, as a result.IMP;Chinese Academy of Science
FIRST COMMISSIONING RESULTS FROM THE NON-SCALING FFAG ACCELERATOR, EMMA
No full textThe first results from commissioning EMMA - the
Electron Model of Many Applications- are summarised in
this paper. EMMA is a 10 to 20 MeV electron ring
designed to test our understanding of beam dynamics in a
relativistic linear non-scaling fixed field alternating
gradient accelerator (FFAG). EMMA will be the world’s
first non-scaling FFAG and the paper will outline the
characteristics of the beam injected in to the accelerator as
well as summarising the results of the 4 sector ‘gantrytype’
commissioning which took place at Daresbury
Laboratory. The paper will report on recent progress made
with the full EMMA ring commissioning, giving details
of tune and orbit measurements as well as their correction
to the desired lattice series.IMP;Chinese Academy of Science
INNOVATIONS IN FIXED-FIELD ACCELERATORS: DESIGN AND SIMULATION
No full textThe drive for higher beam power, high duty cycle, and
reliable beams at reasonable cost has focused world
attention on fixed-field accelerators, notably a broad class
of accelerators termed Fixed-field Alternating Gradient
accelerators, or FFAGs, (with cyclotrons considered a
specific expression or sub-class of FFAGs). Recently, the
concept of isochronous orbits has been explored and
developed for the most general type of FFAG (termed nonscaling)
using powerful new methodologies in fixed-field
accelerator design. One application is high-intensity, in
particular high-energy (GeV), proton drivers which
encounter duty cycle and space-charge limits in the
synchrotron and machine size concerns in the weakerfocusing
cyclotrons. With isochronous orbits, FFAGs are
capable of the high duty cycle, or CW operation, associated
with cyclotrons. Further, their strong focusing enables
smaller losses, and potential energy variability that are more
typical of the synchrotron. With the cyclotron as the current
industrial and medical standard, a competing CW FFAG,
could potentially have broad impact on research, industrial,
and medical accelerators and associated facilities. This
paper reports on new advances in FFAG accelerator
technology, design, and simulation, and also presents
advanced tools developed for all fixed-field accelerators
unique to the code COSY INFINITY[1].IMP;Chinese Academy of Science