Long pulse EBW start-up experiments in MAST

Journal Article · Thu Mar 12 00:00:00 EDT 2015 · EPJ Web of Conferences

DOI:https://doi.org/10.1051/epjconf/20158702007· OSTI ID:1214589

Shevchenko, V. F. ^[1]; Baranov, Y. F. ^[1]; Bigelow, T. ^[2]; Caughman, J. B. ^[2]; Diem, S. ^[2]; Dukes, C. ^[2]; Finburg, P. ^[1]; Hawes, J. ^[1]; Gurl, C. ^[1]; Griffiths, J. ^[1]; Mailloux, J. ^[1]; Peng, M. ^[2]; Saveliev, A. N. ^[3]; Takase, Y. ^[4]; Tanaka, H. ^[5]; Taylor, G. ^[6]

---

1. Culham Science Centre, Abingdon (United Kingdom)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Ioffe Institute, St. Petersburg (Russia)
4. Univ. of Tokyo, Kashiwa (Japan)
5. Kyoto Univ., Kyoto (Japan)
6. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Start-up technique reported here relies on a double mode conversion (MC) for electron Bernstein wave (EBW) excitation. It consists of MC of the ordinary (O) mode, entering the plasma from the low field side of the tokamak, into the extraordinary (X) mode at a mirror-polarizer located at the high field side. The X mode propagates back to the plasma, passes through electron cyclotron resonance (ECR) and experiences a subsequent X to EBW MC near the upper hybrid resonance (UHR). Finally the excited EBW mode is totally absorbed at the Doppler shifted ECR. The absorption of EBW remains high even in cold rarefied plasmas. Furthermore, EBW can generate significant plasma current giving the prospect of a fully solenoid-free plasma start-up. First experiments using this scheme were carried out on MAST [1]. Plasma currents up to 33 kA have been achieved using 28 GHz 100kW 90ms RF pulses. Recently experimental results were extended to longer RF pulses showing further increase of plasma currents generated by RF power alone. A record current of 73kA has been achieved with 450ms RF pulse of similar power. The current drive enhancement was mainly achieved due to RF pulse extension and further optimisation of the start-up scenario.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-09CH11466
• OSTI ID: 1214589
• Journal Information: EPJ Web of Conferences, Vol. 87; ISSN 2100-014X
• Publisher: EDP Sciences
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY