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The slow-wave cyclotron-resonance master ͑CRM͒ oscillator experiment presented in this paper produces output signals that correspond to normal and anomalous Doppler shifts. The table-top low-voltage (Ͻ10 kV͒ CRM device consists of a double stripline waveguide. The metal strips are loaded by dielectric slabs; thus the waveguide supports slow waves with different phase velocities in odd and even quasi-TEM modes. The suppression of axial electric-field components in this waveguide eliminates the Cherenkov interaction as a parasitic effect to the slow-wave CRM. Oscillations are observed in the frequency range 3-15 GHz. Doppler shifts of 30% down and 150% up are measured with respect to the electron cyclotron frequency. These agree with the normal and anomalous tuning conditions, respectively. The dielectric-loaded stripline scheme is discussed for practical slow-wave CRM devices. ͓S1063-651X͑97͒09010-7͔

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Electron beam generation in a diode with different ferroelectric cathodesA ferroelectric cathode is employed in a cyclotron-resonance maser ͑CRM͒. The CRM oscillator device operates at ϳ7 GHz, near the cutoff frequency of a hollow cylindrical cavity. The cathode is made of a PLZT 12/65/35 ceramic with high-dielectric constant (⑀ r ϳ4000). Electrons are extracted from the plasma excited on the cathode surface by ϳ1 kV short rise-time pulses. The use of ferroelectric cathodes may advance the microwave tube technology for various applications.

The intensive research on ferroelectric electron-emission mechanisms in the last decade has resulted in a wide understanding of the physics and characteristics of this plasma-assisted electron source. Nevertheless, practical devices employing this cathode were hardly introduced. In this experimental study, a high-repetition-rate microwave oscillator based on a ferroelectric electron gun has been developed. The device operates as a cyclotron-resonance maser in the gyrotron mode. Microwave pulses exceeding 1.5 kW at ∼7 GHz are measured in repetition rates above 3 MHz and duty cycles of ∼50%. These experimental results encourage the implementation of ferroelectric cathodes in practical high-power microwave tubes.

The Biefeld-Brown is a fascinating effect with which levitation can be reached without moving or rotating elements. Static voltage is applied between asymmetric electrodes and a force towards the small electrode is generated. This effect is studied experimentally in this paper. Using this effect a set of experiments is conducted trying to clarify the relation of the model geometry to the induced force. The results show clear relations of the generated force to the model structure and dimensions. As the asymmetry is stronger, the force is stronger. According to the experimental results, a set of preferred parameters is given to strength the effect. Choosing the geometrical properties properly led to improvement of factor ∼9 in the generated force and efficiency. Nevertheless, some results provides contradictions to earlier models of electrohydrodynamicmic (EHD) describing the effect and reveal unresolved questions regarding this effect.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has raised the need of versatile means for virus decontamination. Millimeter waves are used in biochemical research in dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP/NMR) spectroscopy. However, their efficiency in object decontamination for viruses has not been tested yet. Here we report the high efficiency of 95 GHz waves in killing both coronavirus 229E and poliovirus. An exposure of 2 s to 95 GHz waves reduced the titer of these viruses by 99.98% and 99.375%, respectively, and formed holes in the envelope of 229E virions as detected by scanning electron microscopy (SEM) analysis. The ability of 95 GHz waves to reduce the coronavirus titer to a range of limited infective dose of SARS-CoV-2 for humans and animal models along with precise focusing capabilities for these waves suggest 95 GHz waves as an effective way to decontaminate objects.