| Paper | Title | Other Keywords | Page |
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| MOPCP009 | Development of Power Supplies for 3-Ф, 240 kW RF System with Crowbar Protection for Superconducting Cyclotron at VECC | power-supply, controls, cyclotron, monitoring | 60 |
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| RF system of K-500 super conducting cyclotron at VECC is a complex three phase system operating in the frequency range of 9 MHz to 27 MHz with maximum acceleration potential of around 100 kV feeding to each of three Dee cavities placed in median plane of cyclotron 120° apart through coupling capacitors. Each phase consists of chain of amplifiers and resonator operating in synchronization and at final stage of each phase, a high power water cooled Tetrode Tube (Eimac 4CW 150,000 E) as an RF high power amplifier each capable of delivering 80 kW of RF power. Individual power supplies for biasing Anode (20 kV, 22 Amp), Filament (16 V, 225 Amp), Screen (1600 V, 1 Amp) and grid (-500 V, 0.1 Amp) each for all three high power Tetrode Tubes are designed, developed and commissioned indigenously in VECC Cyclotron building and have been in operation from last few months successfully. Anode supply is common to all three tubes, rated at 20 kV, 22 Amp, 450 kW along with fast acting crowbar protection using Ignitron. This paper describes about the technical challenges in the development of the power supplies and special features of protection systems. | |||
| MOPCP038 | Design Optimization of the Spiral Inflector for a High Current Compact Cyclotron | ion, cyclotron, space-charge, emittance | 129 |
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| VECC is developing a 10 MeV, 5 mA compact proton cyclotron. 80 keV protons from a 2.45 GHz microwave ion source will be injected axially in the central region by a spiral inflector. Because of the high injection energy, the inflector will be comparatively large in size. In order to avoid the beam blow up due to space charge effect and to accommodate the inflector in the small available space in the central region, the design and optimization of the inflector parameters require special attention. This paper describes the design of the spiral inflector and studies its optical properties in the presence of space charge. The beam trajectory calculation from the entrance of the spiral inflector to the central region of the cyclotron have been carried out using the magnetic field data obtained from a 3D code and the electric field data from RELAX3D. We have also checked the orbit centering of the injected beam using a central region code. We have evaluated the effect of linear space charge and carried out optimization of the input beam parameters to minimize the coupling effects between two transverse planes at the inflector exit and to match the acceptance of the central region. | |||
| MOPCP059 | Theoritical Analysis and Fabrication of Coupling Capacitor for K500 Superconducting Cyclotron at Kolkata | vacuum, cyclotron, extraction, radio-frequency | 165 |
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| K500 SC cyclotron has already been constructed and commissioned after spiraling Ne3+ internal beam with 70 nA upto extraction radius(670 mm) at Variable Energy Cyclotron Centre at Kolkata, India. Several problems have been experienced related to the coupling capacitor of the radio frequency system including it's sever burning during commissioning of the cyclotron. Making of the dissimilar joints between alumina ceramic and copper of the coupling capacitor demands the usage of vacuum furnace to avoid the cracking of the ceramic. Therefore exhaustive analysis has been carried out to facilitate the in-house fabrication of the coupling capacitor without using the vacuum furnace in case of emergency. The maximum allowable rate of temperature rise for the ceramic and the optimum thickness ration of the copper to ceramic has been estimated. Finally fabrication of the coupling capacitor has been carried out in-house without employing vacuum furnace. At present the coupling capacitor is performing well as maximum 57 kV DEE voltages were been achieved the till date. This paper presents the details of the analysis and experiences gain during the fabrication of the coupling capacitor. | |||
| MOPCP065 | Closed Loop RF Tuning for Superconducitng Cyclotron at VECC | controls, cyclotron, impedance, pick-up | 180 |
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| The RF system of Superconducting cyclotron has been operational within 9 - 27 MHz frequency. It has three tunable half-wave coaxial cavities as main resonators and three tunable RF amplifier cavities. A PC-based system takes care of stepper motor driven coarse tuning of cavities with positional accuracy ~20 μm and hydraulically driven three couplers and three trimmers. The couplers, in open loop, match the cavity impedance to 50 Ω in order to feed power from RF amplifier. Trimmers operate in closed loop for fine tuning the cavity, if detuned thermally at high RF power. The control logic has been simulated and finally implemented with Programmable Logic Controller (PLC). Precision control of trimmer (~20 μm) is essential to achieve the accelerating (Dee) voltage stability better than 100 ppm and also minimizing the RF power to maintain it. Phase difference between Dee-in and Dee-pick-off signals and the reflected power signals (from cavity) together act in closed loop for fine tuning of the cavity. The close loop PID control determines the final positioning of the trimmer in each power level and achieved the required voltage stability. | |||
| MOPCP067 | Design and Primary Test of Full Scale Cavity of CYCIAE-100 | simulation, cyclotron, impedance, resonance | 183 |
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The engineering of the RF cavity for cyclotron concerns several aspects of the system including vacuum, cooling, mechanical support etc, Sometime it is even more complex than the RF design itself. With limit space in a compact cyclotron, in order to achieve a voltage distribution of 60kV in central orbit and 120kV for outer orbit, a double stem double gap λ by 2 cavities has been designed for CYCIAE-100[1]. The RF resonance of the cavity is simulated [1] by finite integral codes, while the thermal analysis and mechanical tolerance are studied using other approaches [2, 3]. The mechanical design and fabrications is then carried out under these directions, resulting in a full scale cavity model. The simulations and the mechanical design will be reported in this paper, followed with low level measurement results of quality factor, shunt impedance curve along accelerating gap etc. After surface polishing, the measurement yields an unloaded Q value of 9300, which matches well with the simulation with a neglectable difference of several hundreds. The high power test of the cavity will be carried out later, and will be given in separate paper presented at this conference.
[1] Tianjue Zhang,et al, 100 MeV H− Cyclotron as an RIB Driving Accelerator, CYC 2004 [2] Yuanjie Bi, et al, The Study on RF Cavity Tolerance for CYCIAE-100, CYC 2007 [3] S.M. Wei, et al, Thermal Analysis of RF Cavity for CYCIAE-100, CYC 2007 |
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| MOPCP076 | Operational Experience of Superconducting Cyclotron Magnet at VECC, Kolkata | vacuum, controls, cyclotron, cryogenics | 203 |
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| The Kolkata Superconducting cyclotron magnet has been operational in the center 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. | |||
| MOPCP085 | Application of HTS Wire to Magnets | dipole, superconductivity, resonance, synchrotron | 224 |
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| We are developing magnets with High Temperature Superconducting (HTS) wire. A scanning magnet was designed, fabricated, and tested for its suitability as beam scanner. After successful cooling tests, the magnet performance was studied using DC and AC currents. In AC mode, the magnet was operated at frequencies of 30-59 Hz and a temperature of 77 K as well as 10-20 Hz and 20 K. The power loss dissipated in the coils was measured and compared with the model calculations. The observed loss per cycle was independent of the frequency and the scaling law of the excitation current was consistent with theoretical predictions for hysteretic losses in HTS wires. A 3 T dipole maget is under fablication now. | |||