Electron heat transport with non-Maxwellian distributions

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870892· OSTI ID:6970560

Liu, J M; De Groot, J S ^[1]; Matte, J P; Johnston, T W ^[2]; Drake, R P ^[3]

---

1. Plasma Research Group, Department of Applied Science, University of California, Davis, California 95616 (United States)
2. INRS-Energie et Materiaux, C.P. 1020, Varennes, Quebec, J3X 1S2 (Canada)
3. Plasma Physics Research Institute, Lawrence Livermore National Laboratory, L-418, P.O. Box 808, Livermore, California 94551 (United States)

Measurements are presented of electron heat transport with non-Maxwellian (flattopped) distributions due to inverse bremsstrahlung absorption of intense microwaves in the University of California at Davis Aurora II device [Rogers [ital et] [ital al]., Phys. Fluids B [bold 1], 741 (1989)]. The plasma is created by pulsed discharge in a cylindrical vacuum chamber with surface magnets arranged to create a density gradient. The ionization fraction ([similar to]1%) is high enough that charged particle collisions are strongly dominant in the afterglow plasma. A short microwave pulse ([similar to]2 [mu]s) heats a region of the afterglow plasma ([ital n][sub [ital e]]/[ital n][sub cr][le]0.5) creating a steep axial ([ital L][sub [ital T]][similar to]1--10[lambda][sub [ital ei]]) temperature gradient. Langmuir probes are used to measure the relaxation of the heat front after the microwave pulse. Time and space resolved measurements show that the isotropic component of the electron velocity distribution is flat topped [bold (][similar to]exp[[minus]([ital v]/[ital v][sub [ital m]])[sup [ital m]]], [ital m][gt]2[bold )] in agreement with Fokker--Planck calculations using the measured density profile. Classical heat transport theory is not valid both because the isotropic component of the electron velocity distribution is flattopped and the temperature gradients are very steep.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6970560
• Journal Information: Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:11; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700330* -- Plasma Kinetics
Transport
& Impurities-- (1992-)
700350 -- Plasma Production
Heating
Current Drive
& Interactions-- (1992-)
AFTERGLOW
BREMSSTRAHLUNG
ELECTRIC DISCHARGES
ELECTRIC PROBES
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
ENERGY TRANSFER
FERMIONS
HEAT TRANSFER
HEATING
IONIZATION
LANGMUIR PROBE
LASER-RADIATION HEATING
LEPTONS
MICROWAVE RADIATION
PLASMA HEATING
PROBES
RADIATIONS
TEMPERATURE GRADIENTS
TRANSPORT THEORY