Operation of a Sealed-Tube-Vircator High-Power-Microwave Source

Walter, J.; Lynn, C.; Dickens, J.; Kristiansen, M.

doi:10.1109/tps.2012.2192454

Cited by 19 publications

(7 citation statements)

References 8 publications

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“…Two reflex triode virtual cathode oscillators (vircators [17]- [19]), i.e., vacuum diodes with a semitransparent anode (Fig. 3), were constructed for anode material testing.…”

Section: Experimental Setup and Resultsmentioning

confidence: 99%

Anode Materials for High-Average-Power Operation in Vacuum at Gigawatt Instantaneous Power Levels

Lynn

Parson

Scott

et al. 2015

IEEE Trans. Electron Devices

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The thermal behavior of several electrically conducting solids under high incident electron fluence in high vacuum was evaluated. At electron energies of up to ∼200 keV, the depth-dose relationship for electron penetration into the materials was considered, and the resulting energy deposition profile from the surface was revealed to extend to a maximum of ∼175 µm below the surface depending on the anode material. Black body radiation is considered as the major mechanism that balances the power deposited in the material on the timescales of interest. Comparing the radiated power density at the sublimation temperature for different materials, metallic/nonmetallic, revealed that pyrolytic graphite anodes may radiate over 20 times more power than metallic anodes before failure due to sublimation. In addition, transparent pyrolytic graphite anodes (with a thickness on the order of several tens of micrometer) potentially radiate up to 40 times that of metallic anodes, since heating by the electron beam is approximately uniform throughout the thickness of the material, thus radiation is emitted from both sides. Experimental results obtained from titanium and pyrolytic graphite anodes validate the thermal analysis.

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“…Two reflex triode virtual cathode oscillators (vircators [17]- [19]), i.e., vacuum diodes with a semitransparent anode (Fig. 3), were constructed for anode material testing.…”

Section: Experimental Setup and Resultsmentioning

confidence: 99%

Anode Materials for High-Average-Power Operation in Vacuum at Gigawatt Instantaneous Power Levels

Lynn

Parson

Scott

et al. 2015

IEEE Trans. Electron Devices

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“…The virtual cathode is formed when the operating current exceeds the space charge limited current [11][12][13]. A vircator generates microwaves through the oscillation of the virtual cathode formed in the drift tube and the reciprocating motion of electrons between the installed cathode and the virtual cathode [14][15][16]. The vircator has been studied widely due to its strengths, which include its simple structure, broad frequency spectrum, and high-output microwave power [17,18].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Optimum Diameter of the Ring Reflector for an Axial Virtual Cathode Oscillator

Kim

2022

Electronics

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The optimum hole diameter of a ring reflector was experimentally investigated using an axial virtual cathode oscillator (vircator) to enhance its microwave power. The ring reflector enhances the microwave power from the axial vircator by forming a cavity. The ring reflector was installed 9 mm behind the anode. The optimum hole diameter of the ring reflector was analyzed through simulations and experiments by changing the diameter from 60 mm to 160. PIC simulations show that the maximum peak microwave power was generated when the hole diameter was 116 mm and enhanced by 210%. The experiments show similar results to the simulations. The largest peak maximum power was 23.67 MW when the hole diameter was 120 mm. The simulations show that the dominant microwave frequency was formed between 5.33 GHz and 6.7 GHz. The experiments show that the dominant microwave frequency was formed between 5.3 GHz and 5.8 GHz. The frequency trend was approximately similar to that of the simulation results. However, the trend depending on the hole diameter was not as obvious as in the simulations. Although the frequency change was not as clear as in the simulations, experiments show that the hole diameter of the ring reflector affects the vircator operation.

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“…Here, the interface can normally withstand pulsed voltage of the order of several hundred kV or even MV before emitting high-current beams, and the pulse width is about 50∼100 ns and the repetition rate is between 1∼ 100 Hz. Due to the possible surface flashover under high-power flow, the vacuum interface has become the potential limiting factor [2], [3]. Besides, vacuum interface is crucial to ensure the vacuum condition of the high-current beam source, the microwave source, and the radiating antenna in the HPM system [4], [5].…”

Section: Introductionmentioning

confidence: 99%

Developments of Pulsed Electron Beam Sources for High-Power Microwave Applications

et al. 2020

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High-current pulsed electron beam sources are the core components of high-power microwave systems. In order to meet the requirements of future applications, one needs to improve the performance of electron beam sources in terms of vacuum insulation, beam transportation, and thermal management. In this paper, we report about our recent progress in the development of high-current vacuum electron beam sources. In order to meet the vacuum maintenance requirements of high-power microwave tubes, a high-electric field ceramic vacuum interface is designed and fabricated based on the ceramic metal brazing technique. In our experiments, a stable operation of the ceramic vacuum interface is demonstrated in the 10 Hz repetition mode with withstand voltage of larger than 600 kV and pulse width of about100 ns. Besides, a cold cathode is developed using SiC nanowires, and an average beam current density of 1.2 kA/cm 2 is achieved under the electric field strength of 90 kV/cm. Compared with traditional velvet cathodes, the characteristics of the SiC nanowire cathode, such as macro-electrical stability, emission uniformity, and operating life have been significantly improved. Furthermore, a high-current electron beam collector has been developed for relativistic backward wave oscillator tubes. A spiral flume is designed in the collector to meet the requirement of both high specific energy and low flow rate. It shows that the withstand heat flow density is in the order of 10 12 W/m 2 , which is suitable for the long pulse and repetitive operation of the system. These results represent a significant step towards the practical application of long-life high-power microwave systems.INDEX TERMS High-current sources, vacuum interface, ceramic flashover, nano-cathode, collector, thermal control, high-power microwave devices.

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Operation of a Sealed-Tube-Vircator High-Power-Microwave Source

Cited by 19 publications

References 8 publications

Anode Materials for High-Average-Power Operation in Vacuum at Gigawatt Instantaneous Power Levels

Anode Materials for High-Average-Power Operation in Vacuum at Gigawatt Instantaneous Power Levels

Investigation of the Optimum Diameter of the Ring Reflector for an Axial Virtual Cathode Oscillator

Developments of Pulsed Electron Beam Sources for High-Power Microwave Applications

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