Parametric studyoflow frequency rotating structures in high power impulse magnetron sputtering (HIPIMS) discharges

Summary form only given. HiPIMS discharges are able to produce a high density plasma (peak electron density 10¹⁸ - 10²⁰ m^-3) by applying large voltages to a target. Electrons are effectively magnetized by a strong magnetic field (100 mT), and exhibit an E x B drift in the azimuthal direction in the plane of the target. Magnetically confined highly ionized plasmas are known to show a vast range of instabilities ranging from MHz (i.e. modified two stream instability¹) to 10 - 100 kHz range ^2,3,4. We focus here on the low frequency structure rotating in the same direction, at about 10% of the speed of the E x B electron drift. Understanding of the formation and behavior of these spoke like structures is fundamental in determining the overall plasma density, discharge current and cross field transport. In an Argon/Aluminum discharge it has been observed that only a single structure rotating with constant angular speed remains when the power density reaches 4 kW/cm^{2 5}. We theorize that this configuration is one of ”periodic equilibrium”, and we apply a kinetic global model approach to the structure region and evolve the system through a pseudo-transit ⁶. The species densities ne(t), nAr(t) and nAl(t) reach a steady state after only a few periods T = 1/Ω. We present here an improved chemistry model, and an extensive sensitivity analysis of the resulting steady state on the initial conditions of the simulation.