FFS Simulation Project

Focus Fusion Society simulation project

For the past twenty years, a number of laboratories in developing countries have been collaborating on dense plasma focus work through the Asian African Association for Plasma Training. One result of this work has been the development of a simplified computer simulation of the plasma focus. This simulation is not as elaborate as the full three-dimensional simulation that LPP hopes to develop in collaboration with Naval Research Laboratory and George Mason University, but it models many features of the plasma focus process fairly accurately.

Now, FFS volunteer Mathew Schuster has started to work with the program, developed by Dr. Sing Lee of the University of Malaysia, to see how well it matches the experimental results obtained at Texas A&M University and with the Speed-2 machine in Chile. If good agreement is achieved, the model could be used to provide some early guidance for new experiments, while the 3-D simulation is being developed.

Initial results are encouraging. A simulation of results obtained in 2001 at Texas A&M yielded a simulated peak current of 1.12 MA vs the observed value of 1.19MA, a drop in current at the time of the pinch of 0.3 MA for both simulation and observation and a time at pinch of 3.8 microseconds for the simulation and 4.0 microseconds for the observations, an impressive degree of agreement.

The simulation is essentially a one-dimensional model. It uses a set of equations that assumes that the plasma moves in a thin sheath with homogenous properties within that sheath. Like any simulation, it uses the equations to trace the evolution of the process time step-by-time step, using the results of one time-step as the inputs for the next one. More results from the program should be forthcoming in the next few months.