High-Speed Shock Waves in a Magnetic Annular Shock Tube

Abstract

Experiments were carried out with two magnetic field configurations ahead of the shock front, the first with a magnetic field ahead of the shock front in the direction of motion of the shock. In the second configuration the magnetic field ahead of the shock had its principal component in the plane of the shock front and a small component in the direction of the shock motion. The continuum radiation emitted by the shock-heated plasma was measured with photomultipliers. Use of probes to measure the change in the local magnetic field in the shock front was investigated. With the second configuration, shock velocities in excess of 4 × 107 cm/sec were measured in hydrogen. For these high-speed shock waves, shock thicknesses, obtained from measured rise times of the emitted visible radiation, are thinner than the mean free path in the shock-heated plasma, an observation which agrees with a theoretical prediction.

Experimental Investigation of Collision-Free Shocks and Plasmas

“…The measurements of the shock velocity and plasma densities have been reported previously 4 and these results agree with the theoretical values 5 based on the measured drive magnetic field intensity and conditions ahead of the shock. Recently, the change in tl-e magnetic field has been measured with a new type of flux coil.…”

“…It has been previously shown 4 that the shock velocity obtained in a MAST is in agreement with that predicted by using the conservation of mass and momentum equations, the known drive field intensity and the initial conditions ahead of the shock. The measurements of both the plasma radiation, Fig.…”

“…4 A sec after the E breakdown, a 500 MApf capacitor is disr charged through a three turn Ee coil which is embedded in the lucite separator between the electrodes. The frequency of this discharge is of the The drawing is not to scale.…”

“…The magnitude of Be 1 was sufficient to cause a hydrogen ion moving with the same velocity as the shock to have a gyro-radius that is smaller than the channel width (i. e. , annulus spacing). This is an experimentally determined criterion 4 for obtaining high speed shocks in excess of 2. 5 x 107 cm/sec.…”

Gas-Fed Pulsed Plasma Thrusters: Fundamentals, Characteristics and Scaling Laws

“…Originally developing from the magnetic shock tubes [66,67] and applications to fusion research [6], the first plasma guns of many laboratories (see Refs. [8,19,28,35] had long, coaxial electrodes with small radius ratios and propellant injection near the middle of the electrode volume.…”