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Basic operational characteristics of the plasma focus are considered from design perspectives to develop powerful radiation sources. Using these ideas we have developed two compact plasma focus (CPF) devices operating in neon with high performance and high repetition rate capacity for use as an intense soft X-ray (SXR) source for microelectronics lithography. The NX1 is a four-module system with a peak current of 320 kA when the capacitor bank (7.8 F 2 4) is charged to 14 kV. It produces 100 J of SXR per shot (4% wall plug efficiency) giving at 3 Hz, 300 W of average SXR power into 4. The NX2 is also a four-module system. Each module uses a rail gap switching 12 capacitors each with a capacity of 0.6 F. The NX2 operates with peak currents of 400 kA at 11.5 kV into watercooled electrodes at repetition rates up to 16 Hz to produce 300 W SXR in burst durations of several minutes. SXR lithographs are taken from both machines to demonstrate that sufficient SXR flux is generated for an exposure with only 300 shots. In addition, flash electron lithographs are also obtained requiring only ten shots per exposure. Such high performance compact machines may be improved to yield over 1 kW of SXR, enabling sufficient exposure throughput to be of interest to the wafer industry. In deuterium the neutron yield could be over 10 10 neutrons per second over prolonged bursts of minutes.

In order to operate a plasma focus at high axial sheath velocities, the geometry of the inner electrode (anode) of a 3 kJ Mather-type device was modified. Double-stage stepped-anode configurations were tested with the speed-enhanced region sufficiently long for a significant increase in speed but not long enough to allow the development of force-field flow-field separation at the end of the axial phase. Peak axial speeds up to 15 cm μs−1 were achieved. The neutron and soft X-ray productions were found to be sheath-velocity-dependent. A new scaling law for the non-beam component of the neutron yield is proposed.

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Using composite anodes in a 3 kJ plasma focus device operated in deuterium, peak axial sheath velocities up to 15 cm µs −1 are achieved. The temporal characteristics of the soft x-ray emission are investigated by means of filtered PIN diodes. Correlations with hard-x-ray and neutron emission as well as with electrical parameters of the discharge are performed. Two distinct operation regimes are identified regardless of the shape of the anode. Various scaling laws of the soft x-ray production are investigated. We propose a new scaling law for the soft x-ray yield.