Multipactor in low pressure gas

The effect of electron-neutral collisions on the multipactor threshold in a low pressure gas is analyzed in the case when the ionization energy of the gas particles is larger than the impact energy of the oscillating electrons. It is found that a higher microwave power is required to initiate multipactor, since the collisions tend to slow down the electrons. It is also found that the phase limits, within which multipactor can occur, are affected by the presence of the low density gas. Transition to the regime of corona discharges is also discussed.