Experimental validation of the first 1-MA water-insulated MYKONOS LTD voltage adder

The LTD technological approach can result in very compact devices that can deliver fast, high current and high voltage pulses straight out of the cavity without any complicated pulse forming and pulse-compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. Because the output pulse rise time and width can be easily tailored (pulse shaped) to the specific application needs, the load may be a vacuum electron diode, a z-pinch wire array, a gas puff, a liner, an isentropic compression load (ICE) to study material behavior under very high magnetic fields, or a fusion energy (IFE) target. Ten 1-MA LTD cavities were originally designed and built to run in a vacuum or Magnetic Insulated Transmission Line (MITL) voltage adder configuration and, after successful operation in this mode, were modified and made capable to operate assembled in a de-ionized water insulated voltage adder. Special care has been taken to de-aerate the water and eliminate air bubbles. Our motivation is to test the advantages of water insulation compared to the MITL transmission approach. The desired effect is that the vacuum sheath electron current losses and pulse front erosion would be avoided without any new difficulties caused by the de-ionized water insulator. Presently, we have assembled and are testing a two-cavity, water insulated voltage adder with a liquid resistor load. Experimental results of up to 95kV capacitor charging are presented and compared with circuit code simulations.