Current drive and profile control in low aspect ratio tokamaks
The key to the theoretically predicted high performance of a low aspect ratio tokamak (LAT) is its ability to operate at very large plasma current*I{sub p}. The plasma current at low aspect ratios follows the approximate formula: I{sub p} {approximately} (5a{sup 2}B{sub t}/Rq{psi}) [(1 + {kappa}{sup 2})/2] [A/(A {minus} 1)] where A {quadruple_bond} R/a which was derived from equilibrium studies. For constant q{psi} and B{sub t}, I{sub p} can increase by an order of magnitude over the case of tokamaks with A {approx_gt} 2.5. The large current results in a significantly enhanced {beta}{sub t} ({quadruple_bond} {beta}{sub N}I{sub p}/aB{sub t}) possibly of order unity. It also compensates for the reduction in A to maintain the same confinement performance assuming the confinement time {tau} follows the generic form {approximately} HI{sub p}P{sup {minus}1}/{sup 2}R{sup 3}/{sup 2}{kappa}{sup 1}/{sup 2}. The initiation and maintenance of such a large current is therefore a key issue for LATs.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG03-95ER54309
- OSTI ID:
- 102466
- Report Number(s):
- GA-A-22083; CONF-950704-7; ON: DE95017054; TRN: 95:020471
- Resource Relation:
- Conference: 22. European conference on controlled fusion and plasma physics, Bournemouth (United Kingdom), 2-7 Jul 1995; Other Information: PBD: Jul 1995
- Country of Publication:
- United States
- Language:
- English
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