Diffusion coefficient scaling in the Wisconsin levitated octupole
作者:
J. R. Drake,
J. R. Greenwood,
G. A. Navratil,
R. S. Post,
期刊:
Physics of Fluids(00319171)
(AIP Available online 1977)
卷期:
Volume 20,
issue 1
页码: 148-155
ISSN:0031-9171
年代: 1977
DOI:10.1063/1.861703
出版商: AIP
数据来源: AIP
摘要:
Measurements of cross‐field diffusion were made in the levitated octupole using two independent methods. First, the magnitude and scaling ofD⊥with density,n, and field strength,B, were determined by direct measurements of the particle flux onto an internal ring surface. Second, the shape of the density profile and the time decay of the density at the separatrix were compared with solutions of a diffusion equation model. Both methods indicated thatD⊥was proportional ton−1/2and independent ofB. The plasma was created by gun injection into the purely poloidal magnetic field and the initial parameters werene∼5 ×109cm−3,Ti∼20 eV,Te∼5 eV. The observed diffusion scaling can be understood within the framework of vortex diffusion in a high‐dielectric constant plasma if the spectrum of waves is enhanced in energy over thermal levels with an effective temperature,T*, of 104eV.
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