BLUE is a four-cavity LTD system that is presently being assembled at UM. The four cavities were previously part of the 21-cavity Ursa Minor facility at Sandia National Laboratories (hence the name BLUE: Bestowed LTD from the Ursa-minor Experiment). The system is being engineered such that the number of cavities used can be set to 1, 2, 3, or 4. This will allow us to directly test the effects of driver impedance and driver voltage (or machine “stiffness”‘) on load performance while leaving the peak current and rise time nominally unchanged. BLUE will be capable of generating peak currents of 150-200 kA with rise times on the order of 100 ns and open-circuit drive voltages spanning 100-800 kV, depending on the charge voltage and the number of cavities used.
BLUE cavities and test stand upon initial setup at UM
From left to right: Prof Ryan McBride, Research Scientist Nick Jordan, Dr. Steve Exelby, Mark Perreault
For its initial tests, BLUE is being tested in an Inductive Marx Generator (IMG)-like configuration with one of the metal cavity lids replaced by plexiglass. This breaks the alternative current path through the cavity body, and allows the single cavity to be operated without inductive cores. It also produces a nice light-show.