Solenoid-free plasma startup in NSTX using transient CHI

Journal Article · Thu Jan 01 04:00:00 EST 2009 · Nuclear Fusion

DOI:https://doi.org/10.1088/0029-5515/49/6/065006· OSTI ID:1016628

Raman, R ^[1]; Jarboe, T. ^[1]; Mueller, D. ^[2]; Maingi, R. ^[3]

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1. University of Washington, Seattle
2. Princeton Plasma Physics Laboratory (PPPL)
3. Oak Ridge National Laboratory (ORNL)

Experiments in NSTX have now demonstrated the coupling of toroidal plasmas produced by the technique of coaxial helicity injection (CHI) to inductive sustainment and ramp-up of the toroidal plasma current. In these discharges, the central Ohmic transformer was used to apply an inductive loop voltage to discharges with a toroidal current of about 100 kA created by CHI. The coupled discharges have ramped up to > 700 kA and transitioned into an H-mode demonstrating compatibility of this startup method with conventional operation. The electron temperature in the coupled discharges reached over 800 eV and the resulting plasma had low inductance, which is preferred for long-pulse high-performance discharges. These results from NSTX in combination with the previously obtained record 160 kA non-inductively generated startup currents in an ST or tokamak in NSTX demonstrate that CHI is a viable solenoid-free plasma startup method for future STs and tokamaks.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1016628
• Journal Information: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 6 Vol. 49; ISSN 0029-5515
• Country of Publication: United States
• Language: English