Current-shell dynamics in a pulsed electrodynamic plasma accelerator

Journal Article · Sun Apr 01 04:00:00 EST 1973 · Sov. Phys.-Tech. Phys. (Engl. Transl.), v. 17, no. 10, pp. 1659-1669

OSTI ID:4413546

Val'kov, Yu A; Skvortsov, Yu V

Translated from Zh. Tekh. Fiz.; 42: No. 10. 2088-2104(Oct 1972). The acceleration of a current shell in a coaxial accelerator is investigated. The outer electrode has an internal diameter of 10 cm and is 40 cm long; the inner electrode is 3.2 cm in diameter and 56 cm long. The electrodes are copper. Openings for the admission of hydrogen are located in the inner electrode at 37 cm from the face of the accelerator. A pulsed thermal valve with selectable delay time allows the introduction of ~1.5 x 10/sup 19/ hydrogen atoms into the accelerator gap. A condenser bank (5.4 mu F) charged to --25 kV is connected to the accelerator electrodes. The discharge current reaches 114 kA; the half- period is 3.4 mu sec. The hydrogen pressure in the gap before the discharge is ~ 1 mm Hg. the measurements enable one to plot the distribution of magnetic and electric fields in the accelerator gap as a function of time, to determine the dimensions of the current shell and the shape of the line current, to find the time and place of closed current and lead plasmoid formation, and to determine the transition time from an anode potential drop to a cathode drop. These data indicate that a narrow current bridge is formed in the initial stage; the width corresponds to the longitudinal dimensions of the gas cloud. The plasma acceleration then observed is accompanied by a current distribution along the electrodes and an increase in longitudinal dimensions of the bridge. Plasma acceleration ceases with the appearance of closed currents in the system. Interferometer and spectroscope measurements make it possible to plot the distribution of charged-particle densities in the current shell in the accelerator gap as a function of time and to estimate the plasma temperature and impurity localization. Analysis of the experimental data leads to the following conclusions: In electrodynamic accelerators with pulsed admission of hydrogen, the formation of a current shell occurs with the formation of an ionization front, and not in accordance with the snowplow'' or stable current bridge'' models. The spatial distribution of the density and the width of the current shell are explained by the existence of the ionization front. Ion currents play an important part in plasma acceleration. Where a longitudinal electric field exists, it owes its origin to the Hall effect. (auth)

• Research Organization: Originating Research Org. not identified
• NSA Number: NSA-29-004304
• OSTI ID: 4413546
• Journal Information: Sov. Phys.-Tech. Phys. (Engl. Transl.), v. 17, no. 10, pp. 1659-1669, Journal Name: Sov. Phys.-Tech. Phys. (Engl. Transl.), v. 17, no. 10, pp. 1659-1669; ISSN SPTPA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

*PLASMA GUNS-- ELECTRIC CURRENTS
ELECTRODES
HALL EFFECT
HYDROGEN
IONIZATION
N70800* --Physics--Controlled Thermonuclear Research-- Thermonuclear Engineering & Equipment
PLASMA ACCELERATION
PLASMA SHEATH