Numerical simulation of the Helicon Double Layer Thruster concept

The Australian National University and the Laboratoire de Physique et Technologie des Plasmas (LPTP) of Ecole Polytechnique in Palaiseau, France obtained current free helicon double layers in experiments with both electropositive and electronegative gases. The current free double layer has potential application as a plasma thruster. Although considerable progress has been made, at the present time a number of aspects related to this phenomenon are still only partially understood. This paper presents results obtained by numerical simulation of double layer formation, stability and characteristics and to explore the applicability of this concept to a space mission. The analysis has been conducted using a combination of 1-D and 2-D numerical codes. A 1-D code named PPDL was developed specifically for this purpose. It is a hybrid code with Boltzmann electrons and driftkinetic ions, inclusion of dominant 2-D effects and high computational efficiency through implicit nonlinear Boltzmann solver. The 2-D code used was XOOPIC, freely available from University of California at Berkeley. With XOOPIC it was necessary to perform fully electromagnetic simulations with kinetic electrons, resulting in long computational times. A combined approach therefore proved very useful where the 1-D code was used to rapidly screen many different experimental conditions and to identify the right boundary condition. The 2-D code was then used to refine the 1-D results. After the modelization of helicon source, the code is applied to simulate a simple plasma thruster.