Benchmark of particle-in-cell simulations of a Penning-type discharge: Preliminary results

The Penning-type discharge belongs to the E × B family of plasma devices where electrons are magnetized and ions are weakly magnetized or unmagnetized. In a Penning cell, an axial magnetic field, whose magnitude is a few hundreds of Gauss, is generated with the use of permanent magnets or coils that surround a cylindrical anode. A DC electric field is applied between the anode and the cathode planes located at the end of the plasma column. The primary electrons are injected at one end of the column. These discharges operate in the pressure range below a few mTorr, and are used in a large number of applications [1]. Plasma densities are in the range of 1016 – 1018 m-3 and electron temperature between 1 to 10 eV [2]. Coherent structures whose frequency and wavelength are on the order of a few kHz and a few centimetres develop in the direction of the drifting electrons perpendicular to the radial electric and axial magnetic fields. Attempts to characterize the effect of plasma parameters on the structure of the instability and the mechanisms responsible for its formation have been proposed in Ref. [3] using particle-in-cell (PIC) simulations. In the last few years, the community of partially magnetized low temperature plasmas scientists has federated around the LANDMARK project [4] to propose a set of reference benchmarks with the aim of demonstrating the accuracy of numerical solutions [5], [6]. The new test case that we propose is in 2D and corresponds to the radial-azimuthal simulation plane of the rotating spoke in a collisionless Penning discharge. Electrons and ions are injected from a central region. The magnetic field is uniform and perpendicular to the simulation domain. More details about initial conditions can be found in Ref. [4]. At this conference, preliminary results of the timeaveraged profiles of charged particles densities, electron temperature as well as spoke rotation frequencies calculated by 15 research groups worldwide will be shown.