Abstract
Research progresses on Cherenkov and transit-time high-power microwave (HPM) sources in National University of Defense Technology (NUDT) of China are presented. The research issues are focused on the following aspects. The pulse-shortening phenomenon in O-type Cerenkov HPM devices is suppressed. The compact coaxial relativistic backward-wave oscillators (RBWOs) at low bands are developed. The power efficiency in M-Type HPM tubes without guiding magnetic field increased. The power capacities and power efficiencies in the triaxial klystron amplifier (TKA) and relativistic transit-time oscillator (TTO) at higher frequencies increased. In experiments, some exciting results were obtained. The X-band source generated 2 GW microwave power with a pulse duration of 110 ns in 30 Hz repetition mode. Both L- and P-band compact RBWOs generated over 2 GW microwave power with a power efficiency of over 30%. There is approximately a 75% decline of the volume compared with that of conventional RBWO under the same power capacity conditions. A 1.755 GHz MILO produced 3.1 GW microwave power with power efficiency of 10.4%. A 9.37 GHz TKA produced the 240 MW microwave power with the gain of 34 dB. A 14.3 GHz TTO produced 1 GW microwave power with power efficiency of 20%.
Highlights
High-power microwave (HPM) has emerged in recent years as a new technology allowing new application and offering innovative approaches to existing applications
Since the microwave field is weak during the early time of starting oscillation, it is easy to be induced, and a small input signal is sufficient to control the phase of output microwave
The design of the device is described in detail in Ref. 44. Both the power capacity and output mode purity of an X-band overmoded relativistic backward-wave oscillators (RBWOs) are substantially improved through optimizing the profile of the SWSs and geometric parameters of the whole electrodynamic structures
Summary
High-power microwave (HPM) has emerged in recent years as a new technology allowing new application and offering innovative approaches to existing applications. The particle-in-cell (PIC) simulation results reveal that microwaves with power of 10 GW, frequency of 4.3 GHz are generated, and conversion efficiency is 48% when diode voltage is 1.2 MV and beam current 17.3 kA. The microwave with output power of 3.57 GW, frequency of 1.23 GHz, pulse duration of 46 ns and efficiency of 8% is generated under the voltage of 740 kV and the current of 61 kA in the experiment. A microwave with peak power of 6 GW and pulse duration of 80 ns is produced by the L-band RKA at 1.3 GHz when the diode voltage and current are 1 MV and 35 kA, respectively [25]. Typical experimental results are given, which demonstrates a 0.98 GW HPM generated with pulse duration of 95 ns, when the diode voltage and beam current are 650 kV and 4.5 kA, respectively [28]. Beam collecting, electron beam guiding, RF-field breakdown and et al it becomes a focus of our future research to solve the above problems
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