Dimensional Bounds on Vircator Emission

Abstract

Vircators (Virtual Cathode Oscillators) are sources of short-pulsed, high power, microwave (GHz) radiation. An essentially dimensional argument relates their radiated power, pulse energy and oscillation frequency to their driving voltage and fundamental physical constants. For a diode of width and gap 10 cm and for voltages of a few hundred keV the peak radiated power cannot exceed ${\cal O} (\text{30 GW})$ and the broad-band single cycle radiated energy cannot exceed ${\cal O}(\text{3 J})$. If electrons can be accelerated to relativistic energies higher powers and radiated energies may be possible.Comment: 6 p

Assessing Vircators’ Reliability Through Uncertainty and Sensitivity Analyses Using a Surrogate Model

“…Regarding the Vircator's power models, there are some options available in the literature [7], [38], [41], [42]. However, the accuracy of these models is assumed under given conditions.…”

On the Power Limits of an Axially Extracted Virtual Cathode Oscillator

“…Also, they show that in some Cherenkov-Generators and Vircators, that limit can be surpassed. Katz [11] studied the bounds of the Vircator by establishing a power model. Other models calculating the Vircator power are available in the literature but have not been used to determine the Vircator boundaries [12]- [14].…”

“…Other models calculating the Vircator power are available in the literature but have not been used to determine the Vircator boundaries [12]- [14]. These models define the system response as a function of the design parameters [11], [14] [Voltage (V ), anode-cathode gap (d), cathode radius (r c ), drift-tube radius (r dt ), and Anode transparency (T a ), see Fig. 1], or as a function of dependent variables [12], [13].…”

“…1], or as a function of dependent variables [12], [13]. Alyokhin et al [13] define the radiated power as a function of the current injected into the drift-tube (I b ), the spacecharge-limiting current (I scl ), and the rate of particles accumulated between the VC and the cathode (α) [see (1) in [13]], whereas Katz [11] proposes a model in which the power is only a function of V which is a design parameter.…”