Commissioning and power flow studies of the 2.5-MeV Ursa Minor LTD

Ursa Minor is a 21-cavity Linear Transformer Driver (LTD) that has been built to evaluate LTD technology as a driver for electron beam diode research. Initial testing has been conducted at ±90 kV charge. In this configuration the generator has produced 2.0 MV on a 30-ohm MITL when driving an electron beam diode. 2-D PIC simulations of the MITL predict about 15% higher peak voltage and current than seen in experiments. Monte Carlo radiation transport calculations indicate the measured x-ray dose is consistent with the measured diode current and voltage. Triggering experiments indicate that single LTD cavities are insensitive to trigger polarity, whereas the 21-cavity Ursa Minor shows clear sensitivity to trigger polarity.