Characterization of Variations in Power Flow and Photon Generation in HERMES-III Due to Tapering of the Inner and Outer MITL Diameters

Induction Voltage Adder (IVA) machines like HERMES-III (18 MV peak, 650 kA peak, 25 ns radiation pulse) deliver power down <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\sim$</tex> constant-diameter MITLs in order to generate intense bremsstrahlung pulses. We have recently investigated power flow where the constant diameter MITLs have been narrowed to smaller inner and outer MITL diameters by introducing tapered sections. The investigations include: 1) varying the length of each taper, 2) fielding different taper lengths on the cathode- and anode-sides, and 3) staggering the tapers, i.e. tapering the cathode-side first followed by the anode-side. The taper lengths have been varied from 42 cm to 4.5 m. In addition to an array of current monitors along the MITLs, an x-ray pinhole camera (PHC) was mounted on the machine axis, several meters away, so as to characterize the strike pattern of the electron beam on the anode for each configuration. Each configuration has been simulated with PIC codes (Empire and CHICAGO®).