Research topics 1991 onwards

Main areas are plasma (plus electron and ion beams) theory, analytic models and solutions, computational modeling, many-particle (PIC-MCC-RT) simulations, comparisons with laboratory experiments and observations. Main tools are fast PC's, large memories (for millions of particles), and connections to parallel computers.

Simulation requires continual improvement of techniques, from particle weighting, to particle emission/absorption (primary, secondary, photo), to plasma "connection" to external circuits (R,L,C, plus V, I , wave sources), to adding more types of particle collisions and transport, to additions and improvements of diagnostics, to all kinds of ways to accelerate both particle movers and field solvers, to accommodating complicated boundary shapes. All of our contracts are used in this manner.

Devices simulated recently include:

• a traveling-wave tube with a rippled beam with ion collection and ion relaxation oscillations (for ONR);
• a fluorescent lamp, requiring addition of radiation transport radially, seeking sources of losses, to obtain efficiency (for GE), with axial part yet to be added (to obtain whole lamp);
• a series-resonance excited plasma ("resistive-resonant discharge", RRD) with novel properties, robust, stable, locked-in, excited by change-of-state from a decaying, capacitive discharge, candidate for large area plasma, like meter by meter; done without and with an applied magnetic field;
• a laser-plasma wakefield amplifier, seeking world-record level power densities.
  And so on.

PTSG codes are free; download from the Plasma Theory and Simulation Group (PTSG). Help given to users.

Device physics (and some chemistry) include: microwave amplifiers (from low noise to gigawatts), fluorescent lamps, positive-columns, plasma discharges for processing of semiconductors, Q-machines, Malmberg-Penning plasmas, plasma instabilities in hot magnetized plasmas (many!), plasma sheath-core resonances (e.g., series resonances, connections to T-D transverse resonances) and resonant plasma surface waves (connection to T-G waves), applications of the resistive-resonance discharges (RRD's) to plasmas for processing, plasma-wakefield accelerators.