English: Depiction of electron accelerator at DARHT facility at Los Alamos National Lab, NM, USA. To produce X-Rays

Info (DOE / PD): How It Works: Linear Induction Accelerator

The single-pulse linear induction accelerator in each DARHT axis consists of a long row of doughnut-shaped induction cells (only three are shown here in this two-dimensional view) with a large accelerating voltage difference, –200 kilovolts (kV), across the gap between each pair of neighboring cells. The electron beam-pulse travels through the central bore of the cells, receiving a 200-kiloelectronvolt energy kick each time it passes though a gap.

To create the accelerating voltage across the cell gap, a negative voltage pulse from a generator enters each cell (red) and travels down the high-voltage plate, which connects to the inner cylindrical surface of each cell. Together, the high-voltage plate, the cell end plate, and the inner and outer cylindrical surfaces form a conducting cavity. The voltage pulse returning to ground (zero volts) generates a current (red-to-blue transition) around the magnetic cores and an increasing (inductive) magnetic field (not shown) within them.

If the cavity were empty, it would act like a short circuit, drawing too much current from the generator and reducing the voltage pulse length to a few billionths of a second. When filled with the annular magnetic “cores” surrounding the central bore, the cavity acts like an inductance, resisting the flow of current from the generator.