Coaxial accelerator for dense plasmas

Journal Article · Thu Sep 01 04:00:00 EDT 1977 · Sov. J. Plasma Phys. (Engl. Transl.); (United States)

OSTI ID:6927018

Komel'kov, V S; Modzolevskii, V I

This coaxial plasma accelerator has an outer electrode whose diameter (12 mm) is much smaller than that in Marshall guns, and the hydrogen pressure at the beginning of the discharge (30--760 torr) is much higher. It is found that the current in the nozzle flows in a filament 3--8 mm in diameter. This filament represents a plasma continuation of the inner electrode. On the basis of the close correspondence between the curves of the motion of the emitting fronts and the motion of the center of gravity of the current it is concluded that the current is concentrated at the front of the plasma, so that the ''snowplow'' model can be used. Calculations show that this model becomes more appropriate for the process under study as the initial hydrogen pressure in the chamber is raised. The discrepancy between the calculated and measured values increases with decreasing pressure because of the ''sag'' of the current near the insulator and the ablation of this insulator, which lead to an increase in the accelerated mass and to a shunting of the current sheath. Nevertheless, for initial hydrogen pressures in the range 30--760 torr, even if the ''plowing'' is neglected, the density in the frontal plasma sheath reaches 9x10/sup 1/8--6x10/sup 2/0 cm/sup -/3, for velocities of 7.8x10/sup 6/--3.1x10/sup 6/ cm/sec, respectively, at the end of the nozzle. The velocity can be raised by raising the working current and the voltage on the capacitor. The size and shape of the electrodes should also be varied. A film seal is used to achieve plasma acceleration into vacuum. At a film thickness of 50 ..mu.. and a hydrogen pressure of 760 torr under the film the velocity of the plasma front at a point 20 cm beyond the end of the nozzle is relatively constant at 3.3x10/sup 6/ cm/sec. A reduction of the hydrogen pressure under the film does not result in a velocity increase.

• Research Organization: G. M. Krzhizhanovskii State Scientific-Research Energetics Institute
• OSTI ID: 6927018
• Journal Information: Sov. J. Plasma Phys. (Engl. Transl.); (United States), Journal Name: Sov. J. Plasma Phys. (Engl. Transl.); (United States) Vol. 3:5; ISSN SJPPD
• Country of Publication: United States
• Language: English

Related Subjects

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ACCELERATION
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