Diagnostics for kinematics on MTF at NRL

Abstract

The Material Test Facility (MTF) houses a medium caliber EM railgun that is designed for ease of access. As such it is ideal for developing diagnostics for measuring the performance of EM launchers. Multiple, in-situ diagnostics have been fielded on the MTF railgun including field sensors for position location and thermal sensors. Kinematics of the launch package are of particular interest. B-dot loops are the usual method but many such B-dots are required to obtain a detailed evolution of position and velocity. This requires many channels and consumes data acquisition resources. NRL has developed several versions of a Flux Ladder diagnostic which include many pick up loops on one data channel. Some versions have multiple flux ladders interleaved to maintain pulse separation in a single channel but increase overall spatial resolution. On MTF 58 positions were monitored in just three channels.Careful processing has yielded velocity and even acceleration. NRL is also developing a Flux Loop diagnostic that has the potential for continuous kinematics with the time resolution of the digital sampling rate. However, Flux Loops are more sensitive to spurious signal sources. Preliminary results are presented.