Achieving high Q{sub DD} operation in high poloidal beta discharges in TFTR
- Columbia Univ., New York, NY (United States). Plasma Physics Lab.
- Princeton Univ., NJ (United States). Plasma Physics Lab.
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center
Tokamak operation at high poloidal beta ({var_epsilon}{beta}{sub p} {approximately} 1, {var_epsilon}{quadruple_bond} a/R) offers several important advantages to future fusion reactors: low plasma current, high bootstrap current fraction, and the possibility of improved confinement due to equilibrium modification. However, since the plasma current is low at high {var_epsilon}{beta}{sub p}, the achievement of high fusion reactivity generally requires operation at a high Troyon-normalized beta, {beta}{sub N} {quadruple_bond} 10{sup 8} <{beta}> aB{sub t}/I{sub p}, and a high L-mode normalized confinement, H {quadruple_bond} {tau}E/{tau}E,ITER{sub p}. The TFTR high poloidal beta experiments have explored this advanced operating regime in reactor-like conditions, and we have demonstrated techniques that can be used to achieve high Q{sub DD} at high {var_epsilon}{beta}{sub p}. In this paper, we present new results showing that Q{sub DD} as high as 1.3 {times} 10{sup {minus}3}, can be achieved at {var_epsilon}{beta}{sub p} {approximately} 0.85 using transient current profile modification techniques, which nevertheless, maintain high Q{sub DD} for an alpha slowingdown time. Future DT experiments in TFTR will be able to study collective alpha-particle physics in discharges having high {var_epsilon}{beta}{sub p}, high {beta}{sub N}, and evolving current profiles. This paper also illustrates the need for steady-state current profile control to sustain high Q{sub DD} at high {var_epsilon}{beta}{sub p} by presenting recent observations of long-pulse, high {beta}{sub p} discharges in which the current density is allowed to relax naturally to a broad, bootstrap-dominated profile.
- Research Organization:
- Columbia Univ., New York, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-89ER53297; AC02-76CH03073; FG02-90ER54084
- OSTI ID:
- 10175076
- Report Number(s):
- CONF-920913-8; ON: DE92019494
- Resource Relation:
- Conference: 14. international conference on plasma physics and controlled nuclear fusion research,Wurzburg (Germany),30 Sep - 7 Oct 1992; Other Information: PBD: [1992]
- Country of Publication:
- United States
- Language:
- English
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Achieving high fusion reactivity in high poloidal beta discharges in TFTR
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