PDS1 simulations of IEC fusion devices

The PDS1 particle-in-cell, Monte-Carlo-Collision (PIC-MCC) code has been modified for simulating the Inertial Electrostatic Confinement (IEC) device which has multiple collision processes and electrical grids in a spherical geometry. PDS1 can give a detailed account of the transient and steady-state plasma physics occurring in the IEC device. Two experimental single-grid devices and one triple-grid conceptual device were simulated. The University of Illinois' A-device and B-device were simulated under 16 milliTorr of deuterium, a -10-kV cathode grid voltage, and 60 to 80 mA of total grid current. The triple-grid was simulated under 0.2 milliTorr of deuterium and grid voltages of -25 kV, 0 kV, and 20 kV. The secondary electron current emitted from the cathode of the triple-grid device was over 1.5 A. The triple-grid device simulation used electron emitters with a current density of 200 A/m2 and a total current of 234 A. The formation of shallow double and triple wells in the range of 4 to 10% of the cathode grid voltage has been observed in the A-device and the triple-grid device. Only a shallow single well was observed in the B-device. High frequency oscillations in the range of 2 to 5 GHz for the core electrostatic potential have also been observed in the A-device and triple-grid device. From PDS1 simulation data, a plasma core radius can be obtained and an equivalent average energy spread can be calculated from ballistic core radius equations for comparison with the energy spreads used in other simulation codes, such as IXL which solves the collisionless Vlasov equations