Suppression of low frequency plasma instabilities in a magnetized plasma column

Abstract

Optical, wave measurements, and modeling of helicon plasmas for a wide range of magnetic fields This paper reports on a new experimental observation of the suppression of both naturally occurring and driven oscillations in a magnetized, linear plasma column. Detailed measurements are made of the potential structure, density profiles, and wave propagation using Langmuir and emissive probes. These measurements indicate that the decrease in the level of plasma oscillations ͑by factors of 10 or greater͒ is related to the direction of the radial electric field, but may also be connected to a combination of transverse and parallel flows in the plasma.

Rotation of Plasma Layers with Various Densities in Crossed E×B Fields

“…Experimental researches of plasma in crossed E × B fields were started at the beginning of the 1950s in the framework of the activity aimed at the controlled thermonuclear fusion [1][2][3], although the works dealing with gas discharges in crossed fields were initiated at the end of the 19th and the beginning of the 20th centuries [4][5][6]. Nowadays, the experiments devoted to various physical and applied aspects concerning the plasma in crossed fields are intensively carried out on various experimental installations, such as MCX [7], MISTRAL [8], MBX [9], ALEXIS [10], and a number of others. One of the features for plasma created and held in crossed E × B fields is its drift rotation.…”

Upgrades to the Auburn linear experiment for instability studies

“…In ALEXIS and other magnetized linear plasmas, this control is often accomplished through the use of one or more concentric rings, located either at the end of the column opposite the plasma source, 27,30 or at the center of the column using electrodes with a sufficiently low enough opacity that the plasma can pass through the ring or rings. 31 ALEXIS implements the former configuration, with a set of concentric rings that can be independently biased with respect to ground.…”

“…In a similar way, a number of groups have performed laboratory experiments on the generation of shear-modified instabilities with applications to the space plasma environment -e.g., Koepke and co-workers at West Virginia University, [15][16][17] Merlino and co-workers at University of Iowa, [18][19][20] Amatucci and co-workers at the Naval Research Laboratory, [21][22][23] Hatakeyama and co-workers at Tohoku University, [24][25][26] as well as studies by Thomas and co-workers. [27][28][29] An earlier work described the initial construction and operation of the ALEXIS device. 29 In that configuration, ALEXIS made use of thermionically heated filaments and primarily used manual probes as the main diagnostic system.…”