Properties of electrostatic ion-cyclotron waves in a nonuniform magnetic field and their association with strong, magnetized double layers

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:7127396

Cartier, S L

The properties of coherent electrostatic ion-cyclotron (EIC) waves excited under various conditions are described. The experiments were carried out in a cesium Q-machine plasma and in an argon discharge column both having a region of nonuniform magnetic field. In the argon discharge, the waves were examined in the presence of strong, magnetized double layers. The double layers were produced in a weakly ionized plasma by applying a positive potential to a large anode plate located in the diverging magnetic field region. Ionization within the anode sheath is essential to the formation of these double layers. The resulting conical shaped potential structure have extended parallel, oblique, and perpendicular electric field components with respect to the magnetic field. The frequency of the EIC instability is dependent upon the magnetic field strength at the axial location of the parallel electric-field component. In a cesium plasma, the EIC instability is excited by drawing an electron current along the axis of the machine to a small positively biased exciter disk. The waves are quenched when the local ion Larmor radius exceeds the current channel radius; otherwise, the wave frequency, omega/2..pi.., is found to depend on the location of the exciter disk in the nonuniform magnetic field. The formation of ion conics due to the heating of ions by EIC waves and their subsequent flow along diverging B-field lines is presented.

• Research Organization: Iowa Univ., Iowa City (USA)
• OSTI ID: 7127396
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107 -- Fusion Energy-- Plasma Research-- Instabilities
700108* -- Fusion Energy-- Plasma Research-- Wave Phenomena
ALKALI METALS
ARGON
CESIUM
CYCLOTRON INSTABILITY
ELECTRIC DISCHARGES
ELECTRICAL PROPERTIES
ELEMENTS
FLUIDS
GASES
INSTABILITY
METALS
NONMETALS
OPEN PLASMA DEVICES
PHYSICAL PROPERTIES
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
PLASMA WAVES
POSITIVE COLUMN
Q DEVICES
RARE GASES
THERMONUCLEAR DEVICES