Question

what is inhomogeneity scale length in plasma?

Answer 1

Answer:

In the case of an inhomogeneous plasma the density gradient scale length is given by

Radial inhomogeneity scale lengths for radial electric field, ion density, and magnetic-field-aligned (parallel) electron-drift velocity have been measured and interpreted in magnetized, low-temperature, collisionless plasma.  The effect of a narrow layer of inhomogeneity in these parameters on the excitation of electrostatic ion-cyclotron waves is investigated. When the ion Larmor radius ρi is on the order of, or larger than, the half-width at half-maximum σr{Er} of the Gaussian-like, radially localized, radial electric-field profile Er(r), the radial profile of the azimuthal ion rotation velocity, measured using laser-induced fluorescence (LIF), has a peak that, because of finite-Larmor-radius effects, is significantly lower than the peak of the combined radial profile of the E×B and diamagnetic drift velocities. The density depletion is interpreted as resulting from the finite-Larmor-radius ion orbits in the presence of an inhomogeneous electric field with radial scale length σr{Er} ≈ ρi.