THE TIME LAGS OF ELECTRICAL BREAKDOWN IN THE MAGNETIC FIELD. Technical Report No. 5

Technical Report · Mon Aug 20 00:00:00 EDT 1962

OSTI ID:4746827

Nolan, S T; Kendall, H W; Flowers, J W

Using coaxial geometry and a pulsed transverse magnetic field, formative time lags were measured in air, argon, and helium at pressures varying from 0.2 mm Hg to atmospheric. The magnetic field intensities for the measurements varied from 0 to 90 kGauss with a pulse duration up to 140 microseconds. Static breakdown potentials as a function of a transverse magnetic field were measured by Wehrli who suggested that the effect of the magnetic field is the same as an increased gas pressure. Using this equivalent pressure concept, additional theoretical calculations were made concerning the effect on the Townsend coefficients. The time lag measurements show that the addition of a magnetic field has the effect of either increasing or decreasing the overvoltage depending upon the pressure range and the intensity of the magnetic field. The effective increase in overvoltage occurs only below and in the vicinity of the Paschen minimum using relatively small magnetic fields. Effective reduction of the overvoltage and prevention of the gaseous breakdown may be produced at any pressure by the application of a sufficiently large magnetic field. The equivalent pressure concept seems to be a good approximation to the phenomena observed. Measurements of decreased time lags at pressures greater than the Paschen minimum, abrupt cutoff magnetic intensities at low pressures, and exceeding large cutoff magnetic intensities at high pressures indicate that additional physical processes may be involved. Among these may be increased gamma processes due to the decreasing grazing angle of ions on the cathode giving larger secondary yield of electrons, and the magnetic field curving elastically scattered energetic back to the cathode causing secondary emission. (auth)

• Research Organization: Florida. Univ., Gainesville
• NSA Number: NSA-16-033584
• OSTI ID: 4746827
• Report Number(s): TID-16718
• Country of Publication: United States
• Language: English

Related Subjects

BREAKDOWN
ELECTRONS
GASES
IONS
MAGNETIC FIELDS
MEASURED VALUES
NUMERICALS
PHYSICS
PRESSURE
SCATTERING