Stable Operation of a Repetitively Pulsed X-Band Relativistic Backward Wave Oscillator

High-Voltage Drivers Based on Forming Lines with Extended Quasi-Rectangular Pulses for High-Power Microwave Oscillators

“…For example, such a liquid can be MIDEL 7131, which is a synthetic ester dielectric liquid designed to provide an alternative to flammable mineral oil. Since the advent of MIDEL 7131 in the 1970s, this liquid (with very low conductivity and higher permittivity   3.1, as well as superior oxygen and moisture stability) has gained an excellent reputation as an effective dielectric, not only in industrial high-voltage transformers, but also in pulsed power systems as well [14,34]. Besides the possibility of decreasing the PFL length by 17% at a specified pulse width, MIDEL 7131 can provide a gain in the PFL outer dimension due to its high breakdown strength Ebr and the stability of its electric parameters during long-term operation [35].…”

“…Besides the possibility of decreasing the PFL length by 17% at a specified pulse width, MIDEL 7131 can provide a gain in the PFL outer dimension due to its high breakdown strength Ebr and the stability of its electric parameters during long-term operation [35]. For example, if E/Ebr is kept stable at 0.37 or a lower level, a lifetime of up to 10 8 cycles or more can be expected [14]. The breakdown strength (MV/cm) can be expressed by an empirical equation such as that of Ebr for mineral oil, with large-surface electrodes in a weakly inhomogeneous field.…”

“…If the rise time is also sharpened to 10 −9 s or less [4,9], one can attain a picosecond EEE accuracy [10] and phase synchronization of parallel microwave channels [11,12]. In addition, shortening the voltage rise decreases the microwave oscillator transit time [11] and increases the efficiency of the beam-to-wave energy conversion [13,14]. Finally, constant beam parameters within the pulse plateau are needed for mode selection, especially in oversized slow wave structures, where one mode should dominate over competitors for as long as possible [15,16].…”

“…Finally, constant beam parameters within the pulse plateau are needed for mode selection, especially in oversized slow wave structures, where one mode should dominate over competitors for as long as possible [15,16]. The advantages of drivers with distributed PFLs were proved, even by the first experiments on millimeter-wavelength relativistic oscillators [17,18] and, later, on Ka, X, and S-band repetitively pulsed backward wave oscillators [5,[12][13][14][19][20][21][22].…”

“…Our attention was focused on pulse extension, for which we further developed the fruitful idea of pulse width doubling [23] by using an additional, uncharged inner line. This approach has shown obvious advantages in experiments with a double-width PFL [14]. To prove the concept, the laboratory model of a triple-width PFL was created and tested.…”