Inductive voltage adder driven X-ray sources for hydrodynamic radiography

Abstract

Inductive voltage adder (IVA) accelerators were developed to provide high-current (100s of kA) power pulses at high voltage (up to 20 MV) using robust modular components. This architecture simultaneously resolves problems found in conventional pulsed and linear induction accelerators. A variety of high-brightness pulsed X-ray radiographic sources are needed from submegavolt to 16-MeV endpoints with greater source brightness (dose/spot/sup 2/) than presently available. We are applying IVA systems to produce very intense (up to 75 TW/cm/sup 2/) electron beams for these flash radiographic applications. The accelerator electromagnetic pulse is converted to a directed electron beam at the end of a self-magnetically insulated vacuum transmission line. The cantilevered cathode threading the accelerator cavities terminates in a small (l-mm diameter) needle, producing the electron beam which is transported to a grounded Bremsstrahlung converter within a strong (/spl sim/50 T) axial magnetic field. These systems produce mm-sized stable electron beams, yielding very intense X-ray sources. Detailed simulations of the electron beam generation, transport, and target interaction are presented along with scaling laws for the radiation production and X-ray spot size. Experimental studies confirm these simulations and show this reliable, compact, and inexpensive technology scales to 1000-R doses a meter from a mm-diameter source in 50 ns.