Initial Plasma Formation in the GLAST-II Spherical Tokamak
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This paper reports the initial plasma formation in glass spherical tokamak (GLAST-II) with electron cyclotron resonance pre-ionization assisted startup. Initially, a plasma current of 3 kA has been produced for duration of about 0.5 ms after establishing optimum conditions for microwave absorption at 2.45 GHz. Plasma current is then enhanced up to 5 kA by applying a small vertical magnetic field that provides additional plasma heating and shaping. Applied vertical field is optimized experimentally and optimal value is found to be 40 Gauss for this experiment. Plasma current and loop voltage are monitored by using Rogowski coil and toroidal loop of wire. A fast framing camera (5000 fps) is used for temporal investigation of plasma during the discharge scenario. A fast photodiode (BPX-65) and USB4000 spectrometer are used to record the signature of plasma current and the impurity content (O2, H etc.). Cross-sectional average electron temperature is also estimated from plasma resistivity and found to be 6.1 eV for maximum plasma current of 5 kA.
KeywordsGlass spherical tokamak (GLAST) ECR pre-ionization assisted start-up First plasma formation Plasma diagnostics Optical spectrum
The authors would like to express their gratitude to Dr. Badar Suleman (Ex. Member Science), Dr. S.M. Javed Akhter (Member Science) and Mr. Maqbool Ahmed Ch., Director General, TNO for providing guidance throughout the experiment and faithful discussions. The authors also wish to thank the staff of the NILOP and O-Lab Mechanical Workshops for providing technical assistance during fabrication of GLAST. Support from IAEA through CRP No 166997 “on utilization of a network of small magnetic confinement fusion devices of main stream fusion research” is also acknowledged.
- 3.G.M. Vorobyov, D.A. Ovsyannikov, A.D. Ovsyannikov, E.V. Suhov, E.I. Veremey, V.M. Zavadsky, A.P. Zhabko, A.I.P. Conf, Proc. 875, 53 (2006)Google Scholar