Plasma Research Laboratory, RSPhysSE,
Australian National University, ACT 0200 AUSTRALIA
helen.b.smith@anu.edu.au
This paper uses computer models to study breakdown behaviour in rf (13.56 MHz) argon discharges, and is complementary to the experimental work presented in a previous paper by the authors at this conference. A Particle-in-cell simulation is used to determine the breakdown voltage for a pressure range of 20 - 500 mTorr, and an electrode separation of 2 - 20 cm. A series of Paschen-style curves are developed for rf discharges and the effect of the secondary emission coefficient is discussed.
At a few tens of millitorr the time required for the plasma to break down is of the order of a microsecond. However, at very low pressures this time can increase by orders of magnitude to hundreds of microseconds. A semi-analytic global model was developed to study breakdown in this pressure regime. This model includes the effects of metastable atoms, and the importance of their role in breakdown is discussed with reference to measurements made in the experimental system.