Ultrafast LTD's for bremsstrahlung diodes and Z-pinches

Most of the modern high-current high-voltage induction linacs require several stages of pulse conditioning (pulse forming) to convert the multi-microsecond pulses of the Marx generator output to the 40-100 ns pulse required for a cell cavity. This makes the devices large, cumbersome to operate, and expensive. In the present design we eliminate Marxes and pulse-forming networks and instead utilize a new technology recently implemented at the Institute of High Current Electronics in Tomsk (Russia). Each inductive voltage adder cavity is directly fed by a number of fast 100-kV small-size capacitors arranged in a circular array around each accelerating gap. The number of capacitors connected in parallel to each cavity defines the total maximum current. By selecting low inductance switches, voltage pulses as short as 30-60-ns FWHM can be directly achieved. The voltage of each stage is low (100-200 kV). Many stages are required to achieve multi-megavolt accelerator output. However, since the length of each stage is very short (4-10 cm), accelerating gradients of higher than I MV/m can easily be obtained. Each LTD voltage adder can deliver up to 1-MA current to the load. To produce drivers of higher current, many LTD's are connected in parallel. A conceptual design for Saturn three ring diode and Z-pinch and a compact 10-MV 100-kA 60-ns accelerator for advanced radiography will be presented. In both designs the LTD's operate in vacuum and no liquid dielectrics like oil or deionized water will be required. Even elimination of ferromagnetic material (air-core cavities) is a possibility. This makes the devices cheaper, smaller, and lighter than the devices presently utilized which are based on conventional pulsed power technology architecture. We envisage a factor of 3 reduction in size and cost.