Design and Testing of a High-Power Pulsed Load

This paper describes the design and testing of a two-channel 52-kW pulsed load. Its main feature is exceptionally low parasitic inductance, on the order of 200 nH. Such low inductance was needed in view of microsecond high-current pulses; it was realized by a compact design and careful layout. Small size is a prerequisite for minimizing the inductance; it was achieved by forced liquid cooling. Non-inductive bulk resistors were used at a power rating far exceeding their specifications detailed for operation in air and were found adequate for their mission. They were housed in standard stainless steel drums. The cooling liquid (water-propylene-glycol mixture) was circulated through a heat exchanger. Multiple aspects of the design are described, including resistor choice, calculating the load inductance, choice of busbars, details of kinematic scheme, heat transfer, HV, safety and other considerations for cooling agents, etc. Special attention was paid to avoiding turbulent flow that could result in the resistor cracking. Inductance measurements showed close correspondence with the calculations. High-power testing showed reliable operation with overheat about 40 K above ambient.