We report experimental observation of an inverse Doppler shift, in which the frequency of a wave is increased on reflection from a receding boundary. This counterintuitive effect has been produced by reflecting a wave from a moving discontinuity in an electrical transmission line. Doppler shifts produced by this system can be varied in a reproducible manner by electronic control of the transmission line and are typically five orders of magnitude greater than those produced by solid objects with kinematic velocities. Potential applications include the development of tunable and multifrequency radiation sources.

A high-voltage, short-risetime pulse generator is described. The generator consists of a Marx bank, which produces an initial high-voltage pulse, and a ferrite pulse sharpener that reduces the risetime of the pulse. The generator delivers 70-kV, 350-ps risetime pulses into a 50-Ω load.

No abstract

No abstract