Experimental evaluation of a radially symmetric transit-time oscillator

The transit-time effect in a coaxial structure has been used by Arman (1996) to design a low impedance high power microwave device that uses no externally generated magnetic fields and has no confining foils. Luginsland et al. (1997) have developed simple one-dimensional (1D) nonlinear circuit equations that are solved numerically to estimate key device characteristics. A prototype device based on the design by Arman was fabricated and tested. Initial results differed significantly from predictions derived both from ID theory and initial particle-in-cell (PIC) simulations; no RF was generated. After modification of the design simulations to more accurately account for boundary conditions and an over-estimation of diode current, and minor modifications to the prototype hardware design, the device was re-tested. Test results and RF output generally corresponded with the expected results. This paper presents the results of the experimental evaluations, and compares the experimental data with analytical and simulation predictions.