M.G. Mazarakis, R.B. Spielman, K.W. Struve, F.W. Long, (Sandia National Laboratories Albuquerque, NM 87185)
Saturn is a dual-purpose accelerator. It can be operated as a large-area flash x-ray source for simulation testing or as a Z-pinch driver especially for K-line x-ray production. In the first mode, the accelerator is fitted with three concentric ring 2-MV electron diodes, while in the Z-pinch mode the current of all the modules is combined via a post-hole convolute arrangement and driven through a cylindrical array of very fine wires. We present here a point design for a new Saturn driver based on a number of linear inductive voltage adders connected in parallel. A technology recently implemented at the Institute of High Current Electronics in Tomsk (Russia) is being utilized. 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 50-100 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. 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 30-50-ns FWHM can be directly achieved. The voltage of each stage is low (100-200kV). 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 1 MV/m can easily be obtained. The proposed new driver will be capable of delivering pulses of 15-MA, 36-TW, 1.2-MJ, to the diode load, with a pick voltage of 2.2 MV and FWHM of 40ns. And although its performance will exceed the presently utilized driver, its size and cost could be much smaller (1/3). In addition, no liquid dielectrics like oil or deionized water will be required. Even elimination of ferromagnetic material (air-core cavities) is a possibility.
* Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000
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