Penetration and screening of perpendicularly launched electromagnetic waves through bounded supercritical plasma confined in multicusp magnetic field

Abstract

The question of electromagnetic wave penetration and screening by a bounded supercritical ͑ p Ͼ with p and being the electron-plasma and wave frequencies, respectively͒ plasma confined in a minimum B multicusp field, for waves launched in the k Ќ B o mode, is addressed through experiments and numerical simulations. The scale length of radial plasma nonuniformity ͉͑n e / ͑‫ץ‬n e / ‫ץ‬r͉͒͒ and magnetostatic field ͑B o ͒ inhomogeneity ͉͑B o / ͑‫ץ‬B o / ‫ץ‬r͉͒͒ are much smaller than the free space ͑ o ͒ and guided wavelengths ͑ g ͒. Contrary to predictions of plane wave dispersion theory and the Clemow-Mullaly-Allis ͑CMA͒ diagram, for a bounded plasma a finite propagation occurs through the central plasma regions where ␣ p 2 = p 2 / 2 Ն 1 and ␤ c 2 = ce 2 / 2 Ӷ 1͑ϳ10 −4 ͒, with ce being the electron cyclotron frequency. Wave screening, as predicted by the plane wave model, does not remain valid due to phase mixing and superposition of reflected waves from the conducting boundary, leading to the formation of electromagnetic standing wave modes. The waves are found to satisfy a modified upper hybrid resonance ͑UHR͒ relation in the minimum B field and are damped at the local electron cyclotron resonance ͑ECR͒ location.

Observation of electron plasma waves inside large amplitude electromagnetic pulses in a temporally growing plasma

“…29,30 The vacuum TE 11 mode is modified due to the plasma dispersion, hence the axial wave magnetic field amplitude can be expressed in terms of vacuum electric field amplitude E o for a cylindrical waveguide of radius a as 32 B z ðr; hÞ ¼ ðE o =cÞJ 1 ðk c rÞ sin h; where k c (¼ 1.841/a) is the cutoff wave number for the TE 11 mode. The electric field in the presence of plasma gets modified as 11,31 E P ðrÞ ¼ E rP ðr; hÞr þ E hP ðr; hÞĥ;…”

“…10 It is shown that the waves can propagate through plasmas that are overdense in the steadystate approximation. [9][10][11] There are reports on the observation of charge oscillations in preformed steady state plasmas subjected to an external electric field [12][13][14] where the plasma is produced by a different source. The plasma oscillations are analyzed in collision-free and fully ionized regime in understanding the underlying phenomena.…”

“…Here, K ij are the components of the dielectric tensor derived for the k\B o mode of propagation,11,31 D o ¼ ðk 2 o K 11 À k 2 z Þðk 2 o K 22 À k 2 z Þ À k 4 o K 12 K 21; k o is the wave number in free-space, and k z is the axial wave number in presence of plasma. The axial k z and radial k r wave numbers defined by k z r; h ð Þ 2 ¼ k 2 o K 22 r; h ð ÞÀk 2 are implemented in the phase part exp iðk Ár À xtÞ of the wave.…”

Spatially Periodic Electromagnetic Force Field For Plasma Confinement and Control

“…More recent research that is directly or indirectly associated with electrostatic plugging of magnetic cusps includes antihydrogen-related research [10,[31][32][33] and fusion-related research [34]. It should also be noted that recent research has been reported involving plasmas confined or controlled by multiple magnetic cusps [35,36]. The electrostatic-plugging research described in Refs.…”

Electron energy probability function and L-p similarity in low pressure inductively coupled bounded plasma

“…The motivation further arises from the fact that, normally in most wave assisted plasma devices, the heating frequency is maintained constant (e.g., 13.56 MHz for rf discharges and 2.45 GHz in microwave discharges [11][12][13]), and two important parameters that may be varied are the system length (size) and the pressure, which can determine the dynamics of the particles (electrons and ions) present in the discharge. In many actual experiments, it may be inconvenient and quite cumbersome to vary the length of the system.…”