| Paper |
Title |
Page |
| TUPMA097 |
Characteristics of the Magnetic Channel in the Yoke Hole of K-500 Superconducting Cyclotron
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241 |
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- J. Pradhan, R. K. Bhandari, S. Bhattacharya, U. Bhunia, J. Debnath, M. K. Dey, A. Dutta, C. Mallik, Z. A. Naser, S. Paul
DAE/VECC, Calcutta
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The detail magnetic field measurement of K-500 superconducting cyclotron has been carried out. The last magnetic channel of the extraction system placed in the yoke hole of the cyclotron before external beam line is active, unlike others, which are all passive. This channel comprises a coil and a special shaped iron to produce both quadrupole and dipole field for focussing and radially aligning the different ion species coming out from the cyclotron, with the external beam transport line. The magnetic field inside the channel along with the outside stray field has been measured for different channel currents as well as main magnet excitations. A 3-D model of the full magnet is constructed using magneto- static code RADIA [2] to simulate the yoke field. This paper reports the comparative study of measured and calculated field and studies the trajectories for the representative ions through the stray field calculated from the model. The later being used to locate the starting point (or matching point) for the external beam transport line
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| TUPMA113 |
Design of High Current RF Ion Source for Micromachining Applications
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262 |
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- P. Y. Nabhiraj, R. K. Bhandari, C. Mallik, R. Menon
DAE/VECC, Calcutta
- G. G, S. Mohan
IISC, Bangalore
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Liquid Metal Ion Source (LMIS) and Gas Field Emission Ion Source (GFEIS) are the major ones in micromachining applications so far. They have limitations of contaminations and low throughput respectively. Plasma based ion sources can produce heavier ions for higher throughput, lighter ions for fabrication of higher resolution structures, ions for doping, ion assisted direct writing of metallic, oxide, nitride and carbide layers and lines. Considering wide range of applications, a 13.56 MHz inductive coupled plasma (ICP) ion source for producing high brightness ion beams with very low energy spread has been developed. It is a very compact ion source with external helical antenna wound around a 30 mm quartz tube. 1 mA of Argon and 0.5 mA of proton ion beams have been extracted from 2 mm dia aperture in plasma electrode at 3.5 kV extraction potential and ~200W of RF power. Using LabView software and field point modules, an automated plasma diagnostic system has been designed and used to measure the plasma parameters. This paper describes the features of the ion source, ion beams produced, some results of the plasma diagnostics.
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| WEPMA015 |
Characteristics of Beam Extraction System of K500 Superconducting Cyclotron
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357 |
| |
- S. Paul, R. K. Bhandari, J. Debnath, M. K. Dey, A. Dutta, C. Mallik, J. Pradhan
DAE/VECC, Calcutta
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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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| WEPMA104 |
Drive System Instrumentation For VEC SCC Axial-Hole Magnetic Field Measurement
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467 |
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- T. Bhattacharyya, R. K. Bhandari, T. D. Das, C. Mallik, C. N. Nandi, G. P. Pal
DAE/VECC, Calcutta
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Charged particle from the ECR ion source is injected axially into the VEC superconducting cyclotron. The ion beam passes through the vertical section of the axial injection system and the axial hole at the centre of the superconducting cyclotron before reaching the spiral inflector. An accurate knowledge of the magnetic field in the axial hole is essential to properly inject and accelerate the ion beam in the superconducting cyclotron. Three channel F. W. Bell tesla meter with both axial and transverse probes were used to measure the magnetic field. A probe drive with high resolution and repeatability was developed to map the field along this hole from median plane upto 3m above. Stepper motor drives three lead screws which move the hall probe assembly and position them correctly at regular intervals. The basic hardware includes a stepper motor, its drive control unit, PC with National Instrument PCI-6052E data acquisition card and RS232 interface for tesla meter. The GUI developed using Labview takes care of the stepper motor drive control, measurement of the field and statistical error analysis. This paper describes the set up and control system of this measurement.
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| THPMA016 |
Median Plane Magnetic Field Mapping for Superconducting Cyclotron (SCC) in VECC
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652 |
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- A. Roy, T. Bhattacharjee, R. B. Bhole, U. Bhunia, Chaddha, N. Chaddha, J. Debnath, M. K. Dey, A. Dutta, C. Mallik, C. N. Nandi, Z. A. Naser, G. P. Pal, S. Pal, S. Paul, J. Pradhan
DAE/VECC, Calcutta
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The magnetic field upto 29 inch radius on median plane of SCC Magnet (Peak field 5.8T) is measured over its operating range. A client-server system is developed to minimise mapping time and human intervention. The magnetic field is mapped at radial interval of 0.1 inch and angular interval of 1 degree. The complete map of 360 degree comprised of about 100K field points is obtained in less than 100 minutes. The field mapping system is designed to work as PC based TCP Client-Server to reduce the design complexity, system overload and debugging effort. The Server program is developed as windows console in ‘C’ and the Client is developed using LabView to provide a user friendly operation console along with online preliminary display and analysis of field data. This architecture provides a reliable and easily modifiable control s/w. The correctness of the magnet assembly is calculated from the acquired data, which in-turn represents the correctness of measurement system. A detailed study of the magnet characteristic is done. The first harmonics of the fields at different radii are obtained at all magnet excitation and corrected by coil-centering and shims placement.
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| THPMA022 |
Design of the Proposed 250 Mev Superconducting Cyclotron Magnet
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661 |
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- M. K. Dey, R. K. Bhandari, U. Bhunia, J. Chaudhuri, A. Dutta, A. Dutta Gupta, C. Mallik, S. Murali, J. Pradhan, S. Saha, S. S. Sur
DAE/VECC, Calcutta
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VECC has proposed a project for the design and development of a 250 MeV superconducting proton cyclotron, which may be used in therapy. In this paper we describe the preliminary design calculations for the superconducting magnet. Hard-edge approximation method has been adopted for finding the poletip geometry to meet the basic focusing requirements of the beam. The uniform-magnetization method has been applied to calculate the 3D magnetic field distribution due to saturated iron poletips, to verify the beam dynamical issues and optimize the poletip geometry. GM type closed cryo-cooler technology is being considered for steady state liquifaction of evapourated He gas from magnet cryostat.
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| THPMA048 |
Study of Vacuum Related Problems During the Energization of K500 Superconducting Cyclotron
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694 |
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- Z. A. Naser, D. L. Bandapadhaya, R. K. Bhandari, U. Bhunia, J. Debnath, M. Dutta, C. Mallik, S. Paul, A. Polley, J. Pradhan, A. Sur
DAE/VECC, Calcutta
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The K500 superconducting cyclotron main magnet has been commissioned successfully in VECC, Kolkata. During the process of energization, it has been observed that there was vacuum deterioration in the cryostat vacuum chamber with excitations. Detail studies have been carried out to examine the occurrence of such a situation. The electro-magnetic stress in the cryostat wall due to Lorentz force increases with current, and is more pronounced in the median plane of cryostat wherefrom various penetrations come out. This could be the possible reason for the OVC vacuum degradation. The paper reports the observations on vacuum deterioration during energization. An extensive study has been carried out to understand and explain the situation.
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