Energetic electron measurements in the edge of a reversed-field pinch

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Physics of Fluids B; (USA)

DOI:https://doi.org/10.1063/1.859526· OSTI ID:7164837

Ingraham, J C; Ellis, R F; Downing, J N; Munson, C P; Weber, P G; Wurden, G A ^[1]

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1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (US)

The edge plasma of the ZT-40M (Fusion Technol. {bold 8}, 1571 (1985)) reversed-field pinch has been studied using a combination of three different plasma probes: a double-swept Langmuir probe, an electrostatic energy analyzer, and a calorimeter--Langmuir probe. The edge plasma has been measured both with and without a movable graphite tile limiter present nearby in the plasma. Without a limiter a fast nonthermal tail of electrons ({ital T}{congruent}350 eV) is detected in the edge plasma with nearly unidirectional flow along {bold B} and having a density between 2% and 10% of the cold edge plasma ({ital T}{congruent}20 eV). The toroidal sense of this fast electron flow is against the force of the applied electric field. A large power flux along {bold B} is measured flowing in the same direction as the fast electrons and is apparently carried by the fast electrons. With the limiter present the fast electrons are still detected in the plasma, but are strongly attenuated in the shadow of the limiter. The measured scrape-off lengths for both the fast electrons and the cold plasma indicate cross-field transport at the rate of, or less than, Bohm diffusion. Estimates indicate that the fast electrons could carry the reversed-field pinch current density at the edge and, from the measured transverse diffusion rates, could also account for the electron energy loss channel in ZT-40 M. The long mean-free-path kinetic nature of these fast electrons suggests that a kinetic process, rather than a magnetohydrodynamic process that is based upon a local Ohm's law formulation, is responsible for their generation.

• OSTI ID: 7164837
• Journal Information: Physics of Fluids B; (USA), Journal Name: Physics of Fluids B; (USA) Vol. 2:1; ISSN 0899-8221; ISSN PFBPE
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102* -- Fusion Energy-- Plasma Research-- Diagnostics
BEAM ANALYZERS
BOHM CRITERION
CALORIMETERS
CARBON
DIFFUSION
ELECTRIC FIELDS
ELECTRIC PROBES
ELECTROSTATIC ANALYZERS
ELEMENTAL MINERALS
ELEMENTS
END EFFECTS
GRAPHITE
LANGMUIR PROBE
LIMITERS
MEASURING INSTRUMENTS
MINERALS
NONMETALS
OHM LAW
PINCH EFFECT
PLASMA
PLASMA DIAGNOSTICS
PLASMA DRIFT
PROBES
REVERSE-FIELD PINCH
ZT-40 DEVICES