Effect of rf driving frequency on peripheral high energy electrons in a magnetically expanding plasma reactor

Two operational rf driving frequencies of 2 and 13.56 MHz are employed in a 14-cm-diameter radio frequency (rf) plasma source under an expanding magnetic field. The changes the radial profiles ion saturation current electron temperature observed magnetically when changing frequency. Peripheral high electrons detected for higher case, which is consistent with previous studies, implying localized heating radially outer region near antenna transport along However, it disappears lowering frequency, would be due to increase skin depth. Therefore, present results demonstrate that power absorbed entire regions discharge tube lower cases, respectively. As result ionization induced by peripheral field, density field case than resulting larger thrust as measured pendulum target technique.