Lawrence Berkeley National Laboratory

We simulate fusion power plant driver efficiency by pulsing small induction cores at 5 Hz (a typical projected power plant repetition rate), with a resistive load in the secondary winding that is scaled to simulate the beam loading for induction acceleration. Starting from a power plant driver design that is based on other constraints, we obtain the core mass and acceleration efficiency for several energy ranges of the driver accelerator and for three magnetic alloys. The resistor in the secondary is chosen to give the same acceleration efficiency, the ratio of beam energy gain to energy input to the core module (core plus acceleration gap), as was computed for the driver. The pulser consists of a capacitor switched by FETs, Field Effect Transistors, which are gated on for the desired pulse duration. The energy to the resistor is evaluated during the portion of the pulse that is adequately flat. We present data over a range of 0.6 to 5 mu s pulse lengths. With 1 mu s pulses, the acceleration efficiency at 5 Hz is measured to be 75 percent, 52 percent, and 32 percent for thin-tape-wound cores of nanocrystalline, amorphous, and 3 percent silicon steel materials respectively, including only core losses. The efficiency increases for shorter pulse durations.