PENETRATION OF A HIGH-FREQUENCY FIELD IN A LOW-PRESSURE PLASMA

Comparisons between calculated and directly measured values of radial penetration of axially directed magnetic fields in cylindrical plasmas have been effected. Using elementary theory the curve of field intensity vs radius was calculated which matched the measured intensity. The level of conductivity demanded by theory was then compared with that deduced directly from the measured ne and Te. When the experimental conditions corresponded closely to those assumed in the elementary theory development, the conductivities agreed well. The investigation was made in 5-cm-diam noble gas discharges at 5-500 μ with steady 500 kc/sec fields of 50-80 G at the plasma surface. Te and ne were measured vs radius; the ranges of values were Te = 2-12 eV and ne = 1011-10 14 per cm3. The penetrations measured were those of the fields producing the plasmas.