Radio-frequency-sheath-driven edge plasma convection and interaction with the H mode

Journal Article · Fri Oct 01 04:00:00 EDT 1993 · Physics of Fluids B; (United States)

DOI:https://doi.org/10.1063/1.860832· OSTI ID:6212825

D'Ippolito, D A; Myra, J R ^[1]; Jacquinot, J; Bures, M ^[2]

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1. Lodestar Research Corporation, 2400 Central Avenue, Boulder, Colorado 80301 (United States)
2. JET Joint Undertaking, Abingdon, Oxfordshire OX14 3EA (United Kingdom)

It is shown that radio-frequency (rf) antenna sheaths can bias the edge plasma potential and drive steady-state convective cells in the scrape-off layer (SOL). The resulting [bold E][times][bold B] convective flow opposes the direction of the sheared flow in the SOL induced by the radially decaying Bohm sheath potential. A two-dimensional fluid simulation shows that the interaction of the opposing poloidal flows produces secondary vortices, which connect the edge of the confined plasma to the antenna limiters, when the antenna--plasma separation is typically of order a few times the local electron skin depth at the antenna. Estimates for typical tokamak edge parameters suggest that the transit time of particles and energy across these vortices is rapid enough to cause the broadening of SOL density and temperature profiles observed during high-power heating with ion cyclotron range of frequency (ICRF) antennas in monopole phasing. Radio-frequency-sheath-driven convection is also a good candidate to explain the phasing dependence of the global confinement properties of ICRF H modes on the Joint European Torus (JET) [Fusion Technol. [bold 11], 13 (1987)]. A comparison of the JET H-mode data with the theoretical modeling supports this idea and suggests that ICRF convection may be a useful tool to spread the heat deposition in the divertor and to extend the lifetime of the H mode.

• OSTI ID: 6212825
• Journal Information: Physics of Fluids B; (United States), Journal Name: Physics of Fluids B; (United States) Vol. 5:10; ISSN PFBPEI; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700350* -- Plasma Production
Heating
Current Drive
& Interactions-- (1992-)
ANTENNAS
CLOSED PLASMA DEVICES
CONFINEMENT
CONVECTION
DIVERTORS
ELECTRICAL EQUIPMENT
ELECTROMAGNETIC RADIATION
ENERGY TRANSFER
EQUIPMENT
HEAT TRANSFER
MASS TRANSFER
PLASMA CONFINEMENT
PLASMA SHEATH
RADIATIONS
RADIOWAVE RADIATION
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
VORTICES