High poloidal beta equilibria in TFTR limited by a natural inboard poloidal field null

Technical Report · Mon Jul 01 00:00:00 EDT 1991

DOI:https://doi.org/10.2172/5440464· OSTI ID:5440464

Sabbagh, S A; Gross, R A; Mauel, M E; Navratil, G A ^[1]; Bell, M G; Bell, R; Bitter, M; Bretz, N L; Budny, R V; Bush, C E; Chance, M S; Efthimion, P C; Fredrickson, E D; Hatcher, R; Hawryluk, R J; Hirshman, S P; Janos, A C; Jardin, S C; Jassby, D L; Manickam, J ; McCune, D C; McGuire, K M; Medley, S S; Mueller, D; Nagayama, Y; Ow,

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1. Columbia Univ., New York, NY (United States). Dept. of Applied Physics

Recent operation of the Tokamak Fusion Test Reactor TFTR, has produced plasma equilibria with values of {Lambda} {triple bond} {beta}{sub p eq} + l{sub i}/2 as large as 7, {epsilon}{beta}{sub p dia} {triple bond} 2{mu}{sub 0}{epsilon}/{much lt}B{sub p}{much gt}{sup 2} as large as 1.6, and Troyon normalized diamagnetic beta, {beta}{sub N dia} {triple bond} 10{sup 8}<{beta}{sub t}{perpendicular}>aB{sub 0}/I{sub p} as large as 4.7. When {epsilon}{beta}{sub p dia} {approx gt} 1.25, a separatrix entered the vacuum chamber, producing a naturally diverted discharge which was sustained for many energy confinement times, {tau}{sub E}. The largest values of {epsilon}{beta}{sub p} and plasma stored energy were obtained when the plasma current was ramped down prior to neutral beam injection. The measured peak ion and electron temperatures were as large as 24 keV and 8.5 keV, respectively. Plasma stored energy in excess of 2.5 MJ and {tau}{sub E} greater than 130 msec were obtained. Confinement times of greater than 3 times that expected from L-mode predictions have been achieved. The fusion power gain. Q{sub DD}, reached a values of 1.3 {times} 10{sup {minus}3} in a discharge with I{sub p} = 1 MA and {epsilon}{beta}{sub p dia} = 0.85. A large, sustained negative loop voltage during the steady state portion of the discharge indicates that a substantial non-inductive component of I{sub p} exists in these plasmas. Transport code analysis indicates that the bootstrap current constitutes up to 65% of I{sup p}. Magnetohydrodynamic (MHD) ballooning stability analysis shows that while these plasmas are near, or at the {beta}{sub p} limit, the pressure gradient in the plasma core is in the first region of stability to high-n modes. 24 refs., 10 figs.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 5440464
• Report Number(s): PPPL-2775; ON: DE91016214
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
TFTR TOKAMAK
HIGH-BETA PLASMA
PLASMA CONFINEMENT
BALLOONING INSTABILITY
CONFINEMENT TIME
MHD EQUILIBRIUM
NEUTRAL ATOM BEAM INJECTION
NEUTRONS
NON-INDUCTIVE CURRENT DRIVE
PRESSURE GRADIENTS
BARYONS
BEAM INJECTION
CONFINEMENT
ELEMENTARY PARTICLES
EQUILIBRIUM
FERMIONS
HADRONS
INSTABILITY
NUCLEONS
PLASMA
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
700101* - Fusion Energy- Plasma Research- Confinement
Heating
&amp; Production