Magnetic field dependence of asymmetry-induced transport: A new approach
- Physics Department, Occidental College, Los Angeles, California 90041 (United States)
A new technique is used to experimentally study the dependence of asymmetry-induced radial particle flux {gamma} on an axial magnetic field B in a modified Malmberg-Penning trap. This dependence is complicated by the fact that B enters the physics in at least two places: in the asymmetry-induced first order radial drift velocity v{sub r}=E{sub {theta}}/B and in the zeroth order azimuthal drift velocity v{sub {theta}}=E{sub r}/B. To separate these, it is assumed that the latter always enters the physics in the combination {omega}-l{omega}{sub R}, where {omega}{sub R}(r)=v{sub {theta}}/r is the column rotation frequency and {omega} and l are the asymmetry frequency and azimuthal mode number, respectively. Points where {omega}-l{omega}{sub R}=0 are then selected from a {gamma} versus r versus {omega} data set, thus insuring that any function of this combination is constant. When the selected flux is plotted versus the density gradient {nabla}n, a roughly linear dependence is observed, showing that the assumption is valid and that the diffusive contribution to the transport has been isolated. The slope of a least-squares fitted line then gives the diffusion coefficient D{sub 0} for the selected flux. Varying the magnetic field, it is found that D{sub 0}{proportional_to}B{sup -1.33{+-}}{sup 0.05}. This does not match the scaling predicted by resonant particle transport theory.
- OSTI ID:
- 21106160
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 3 Vol. 15; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Transport suppression by diamagnetic phase shift as a possible mechanism to the L to H transition
Experimental test of the resonant particle theory of asymmetry-induced transport