| Paper |
Title |
Page |
| TUPMA116 |
Periodic Ion Current Burst in 6.4 GHz ECR Source
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268 |
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- G. S. Taki, R. K. Bhandari, P. R. Sarma
DAE/VECC, Calcutta
- A. G. Drentje
KVI, Groningen
- T. Nakagawa
RIKEN/RARF/CC, Saitama
- P. K. Ray
Bengal Engineering and Science University, Howrah
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We studied the enhancement in extracted ion current in the 6.4 GHz ECR ion source at VECC, Kolkata by inserting a negatively biased disc in the main stripping stage. In addition to the expected increase in current, we observed a sudden jump in the current at some low bias voltage. The jump amplitude is larger for higher charge states. In order to understand the origin of the jump, we recently measured the time spectra of high charge state ion current for neon. The time spectra revealed the presence of a burst frequency in the kilohertz range. This frequency shows a correlated jump with the ion current described above. Another feature is that the observed burst frequency shows a good linear correlation with the extracted ion current. This may signify that current per burst is a constant factor, higher current means that there are more number of bursts.
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| WEPMA005 |
Magnetic Field Calculations of a 10 MeV High Current Compact Cyclotron
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342 |
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- V. S. Pandit, A. Goswami, P. R. Sarma, P. Sing Babu
DAE/VECC, Calcutta
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A 10MeV, 5-10mA 4-sector compact proton cyclotron, is being developed at VECC. A 2.45 GHz microwave ion source will produce ~30mA of proton beam at 100keV. It will be bunched and injected axially in the central region of the cyclotron where a spiral inflector will place the beam on the proper orbit. Two delta type resonators located in the opposite valleys will be used for providing acceleration to the beam. Beam will be extracted using an electrostatic deflector. The main aim of this project is to study and settle various physics and technological problems associated with the handling of high intensity beams. In this paper we present the results of design studies of the main magnet. The conceptual dimensions of the magnet and the properties of equilibrium orbits were first obtained using hard edge approximations and matrix method. The primary size of the magnet was estimated using 2D POISSON code. Finally a 3D code was utilized for the field calculation and optimization. The profile of magnet sectors was optimized to get the desired values of isochronous field and the betatron tunes.
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| THPMA020 |
Ideal Coil-Shape for Perfect Field in Superconducting Sextupole Magnets
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658 |
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- P. R. Sarma
DAE/VECC, Calcutta
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Coil dominated superconducting magnets have become essential components in high energy accelerators. Such magnets need to have very good field quality in order to preserve the beam emittance when it passes through the magnets a large number of times. It is well-known that the coil-shape generated by two displaced elliptic current distributions of opposite signs produce a perfect dipole field in the overlapping region. Similarly two intersecting concentric elliptic current distributions produce the perfect quadrupole field. The coil-shapes of practical superconducting magnets which are used in LHC, RHIC etc. are variations of such ideal designs. No mention of ideal coil-shape for a perfect superconducting sextupole magnet is available in the literature. In the present work we have explored the field produced by various coils shapes and found a coil shape which is capable of generating the perfect sextupole field. Parametric equation has been given for the x-y profile of the boundary of the coil cross-section. This finding should be useful in designing practical sextupole coils.
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