PLASMA PROPULSION BY MEANS OF A HELICAL TRANSMISSION LINE

Technical Report · Fri Jul 20 04:00:00 EDT 1962

OSTI ID:4773401

Mayfield, E B; Meyer, R X; Head, R M; Huddlestone, R H

Experimental and theoretical studies of plasma propulsion using a helical transmission line to generate a moving magnetic field were conducted. Preliminary results from a 10-kv line encouraged the building of a similar. but larger, 25-kv line. Recent development of 0.5 mu f capacitors capable of ringing at 25 kv with a frequency of 1.05 Mc and small enough to install on a transmission line made possible its construction. Results reported were obtained with the 25-kv line. The system consists of a conical electrical discharge driver, shock tube, and helical transmission line. The propellant gas is H/sub 2/ at an initial pressure of 175 mu (particle density 6 x 10/sup 15/ cm/sup -3/). The shock tube driver uses a capacitor bank of 8 mu f at 25 kv and rings at 250 kc/sec. At 10 cm from the ring electrode where the shock enters the transmission line, the shock has a velocity of 16 cm/ mu sec which decays to 3 cm/ mu sec as it leaves the transmission line 115 cm from the electrode. The helical line has a phase velocity of 11.3 cm/ mu sec and a capacitance per length of 13.8 mu f/m. This gives an impedance of 0.615 ohm and an initial current of 40,700 amperes. From this the axial magnetic field is calculated to be 7100 gauss; the radial magnetic field is calculated to be 1400 gauss. Results obtained with a rotating mirror streak camera along the axis of the system show that, when the magnetic field is initiated 4 to 6 mu sec behind the ionizing shock (30--40 cm in the tube), the shock velocity is maintained at the phase velocity of the transmission line --11 cm/ mu sec. Photomultiplier and magnetic field probes indicate that the luminous shock in the gas travels with the magnetic field at the phase velocity of the line. A pressure bar device is used to measure the change in impulse due to the magnetic field. (auth)

• Research Organization: Aerospace Corp. Physical Research Lab., El Segundo, Calif.
• NSA Number: NSA-16-032477
• OSTI ID: 4773401
• Report Number(s): DCAS-TDR-62-145; TDR-169(3210-
• Country of Publication: United States
• Language: English

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