The mining industry is heavily dependent on energy-intensive processes, such as rock breakage, which leads to significant operational costs. This paper explores microwave-assisted rock breakage as an innovative method to enhance the efficiency of comminution within the mining industry. It introduces a system that employs a Klystron microwave power source with a maximum output of 7.5 MW, using a $\mathrm{TM}_{010}$ single-mode cavity at 3 GHz, to channel energy inside a specially designed rock cavity. The paper emphasizes the importance of designing an efficient microwave cavity for this system, focusing on the cavity’s design and simulation. Through both simulated results (using HFSS software) and experimental observations, the study reveals the promising application of microwave technology in the field of mining. The simulated frequency response of the designed cavity (S11) is −22 dB, it demonstrates significant potential for reducing both energy consumption and associated costs. Additionally, the designed cavity is fabricated from aluminum and filled with polyether ether ketone material. The measured frequency response (S11) of the cavity at 3 GHz is −17 dB.

Two coaxial waveguide bend mode converters that transform coaxial transverse electromagnetic mode to TE11 coaxial waveguide mode are presented in this paper. Both converters are designed and optimized on the basis of the strictly derived mode coupling coefficients. Conversion efficiencies of both converters are over 99% and the power-handling capacities reach a gigawatt level. The combined dual-bend mode converter is fabricated and tested. The experimental results coincide well with the theoretical calculations and simulations, which demonstrates the feasibility of the designed converter.

To produce pulses with good flat-top quality, pulse-forming lines (PFLs) have been widely used in the field of Tesla-type pulse generators. To shorten the physical length of the PFL, a double-width PFL (DWPFL) is proposed that doubles the output pulse width while maintaining flat-top quality. A repetitively 10 GW Tesla-type long-pulse generator producing pulses with flat-top width of about 110 ns was developed with a coaxial DWPFL to produce high-current electron beams. Electron beams of about 10 GW with flat-top widths of about 110 ns were obtained on a planar vacuum diode load. With this pulse generator and a C-band high-power microwave system, microwaves of ~2.2 GW power and full-width at half-maximum of 101 ns were generated. The experiment demonstrates the feasibility and ideal output waveform quality of the DWPFL.

Efficient generation regime with a high power output has been experimentally realized in a klystron-like relativistic backward wave oscillator, in which a modulation cavity is inserted between the slow wave structure to decrease the energy spread of modulated beam electrons, and an extraction cavity is employed at the end of the slow wave structure to further recover energy from the electron beam. At a guiding magnetic field of 2.2 T, a microwave pulse with power of 6.5 GW, frequency of 4.26 GHz, pulse duration of 38 ns, and efficiency of 36% was generated when the diode voltage was 1.1 MV, and diode current was 16.4 kA. When the diode voltage was 820 kV, efficiency up to 47% with microwave power 4.4 GW was also realized experimentally.