Power balance consideration of density jumps in pulsed helicon discharges

The time evolution of the plasma density is investigated in pulsed helicon discharges. During the initial period of 10 msec, the densities are found to be higher with unstable oscillations than the rest of pulse duration, and they are decreased to steady state values when the magnetic field (the rf frequency) is higher (lower) than the threshold value. These density variations are discussed using the stability condition in power balance.