Backward-Wave Oscillator Operating in Low Magnetic Fields Using a Hybrid-TE<sub>11</sub> Mode

Chipengo, Ushemadzoro; Nahar, Niru K.; Volakis, John L.

doi:10.1109/ted.2017.2722869

Cited by 11 publications

(5 citation statements)

References 27 publications

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“…[10][11][12][13][14][15][16][17][18] However, a very few experiments have been carried out to actually generate high power microwaves with an electron beam passing through an MTM structure. [19][20][21][22][23] At MIT, in our previous experiment, 19 we built a structure with two MTM plates loaded in a waveguide with dimensions below the cut-off of the TM 11 mode.…”

Section: Introductionmentioning

confidence: 99%

High power long pulse microwave generation from a metamaterial structure with reverse symmetry

Stephens

Mastovsky

et al. 2018

Physics of Plasmas

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Experimental operation of a high power microwave source with a metamaterial (MTM) structure is reported at power levels to 2.9 MW at 2.4 GHz in full 1 μs pulses. The MTM structure is formed by a waveguide that is below cutoff for TM modes. The waveguide is loaded by two axial copper plates machined with complementary split ring resonators, allowing two backward wave modes to propagate in the S-Band. A pulsed electron beam of up to 490 kV, 84 A travels down the center of the waveguide, midway between the plates. The electron beam is generated by a Pierce gun and is focused by a lens into a solenoidal magnetic field. The MTM plates are mechanically identical but are placed in the waveguide with reverse symmetry. Theory indicates that both Cherenkov and Cherenkov-cyclotron beam-wave interactions can occur. High power microwave generation was studied by varying the operating parameters over a wide range, including the electron beam voltage, the lens magnetic field, and the solenoidal field. Frequency tuning with a magnetic field and beam voltage was studied to discriminate between operation in the Cherenkov mode and the Cherenkov-cyclotron mode. Both modes were observed, but pulses above 1 MW of output power were only seen in the Cherenkov-cyclotron mode. A pair of steering coils was installed prior to the interaction space to initiate the cyclotron motion of the electron beam and thus encourage the Cherenkov-cyclotron high power mode. This successfully increased the output power from 2.5 MW to 2.9 MW (450 kV, 74 A, 9% efficiency).

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Section: Introductionmentioning

confidence: 99%

High power long pulse microwave generation from a metamaterial structure with reverse symmetry

Stephens

Mastovsky

et al. 2018

Physics of Plasmas

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“…BWO devices can operate for generation of multi-Gigawatt level peak power at low magnetic field and peak experimental microwave power in excess of 7.6 GW has been realized with 42% efficiency [7]. However, these devices are highly overmoded, having cross section diameter to operating wavelength ratio in between 1 & 2 or more [6][7][8][9][10]. The overmoded structure has an advantage of increased power handling capability.…”

Section: Introductionmentioning

confidence: 99%

“…The overmoded structure has an advantage of increased power handling capability. Limiting factors in these devices is the mode competition which limits the microwave conversion efficiency for a desired mode [7,8]. Devices having normal cross sections do suffer from pulse shortening and field breakdown at much lower levels of peak microwave power [11,12].…”

Section: Introductionmentioning

confidence: 99%

An Efficient Sub-Gigawatt Level X-band BWO at Low Guiding Magnetic Field

Jadab,

Chandra,

Singh

et al. 2024

Preprint

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“…Typically, maximum efficiency claimed is between 20% and 40%. 16,17 Working efficiency of the RBWO is always depends on beam-wave interaction, which can be achieved by stable beam transportation of high current beam through slow wave structure (SWS). 18 There are different methods suggested to transport high current sheet electron beam, like axial magnetic field arrangement, 19 cusped magnetic arrangement, 20 wiggler magnetic field arrangement, 21 and so on.…”

Section: Introductionmentioning

confidence: 99%

“…Though sheet beam driven BWO can generate high power, still its efficiency enhancement is always an open issue. Typically, maximum efficiency claimed is between 20% and 40% 16,17 . Working efficiency of the RBWO is always depends on beam‐wave interaction, which can be achieved by stable beam transportation of high current beam through slow wave structure (SWS) 18 .…”

Section: Introductionmentioning

confidence: 99%

Enhanced efficiency of C‐band sheet beam driven backward wave oscillator guided by periodic magnetic field

Banerjee¹,

Hadap

Saxena³

et al. 2020

Micro & Optical Tech Letters

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In this article we present the effect of periodic magnetic field on the efficiency of a sheet beam driven C-band backward wave oscillator (operational in Megawatt power regime) through MAGIC3D PIC simulation. At 90 kV beam energy, 200 A beam current, and 0.6 T average magnetic field, our results depict an efficiency of nearly 70% due to improved electron beam confinement and electron bunching. A qualitative comparison is shown for efficiency through the same slow wave structure, guided by a uniform axial magnetic and the proposed periodic magnetic field. Efficiency enhancement of nearly 20% is observed in case of periodic magnetic field.

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Backward-Wave Oscillator Operating in Low Magnetic Fields Using a Hybrid-TE₁₁ Mode

Cited by 11 publications

References 27 publications

High power long pulse microwave generation from a metamaterial structure with reverse symmetry

High power long pulse microwave generation from a metamaterial structure with reverse symmetry

An Efficient Sub-Gigawatt Level X-band BWO at Low Guiding Magnetic Field

Enhanced efficiency of C‐band sheet beam driven backward wave oscillator guided by periodic magnetic field

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Backward-Wave Oscillator Operating in Low Magnetic Fields Using a Hybrid-TE11 Mode

Cited by 11 publications

References 27 publications

High power long pulse microwave generation from a metamaterial structure with reverse symmetry

High power long pulse microwave generation from a metamaterial structure with reverse symmetry

An Efficient Sub-Gigawatt Level X-band BWO at Low Guiding Magnetic Field

Enhanced efficiency of C‐band sheet beam driven backward wave oscillator guided by periodic magnetic field

Contact Info

Product

Resources

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Backward-Wave Oscillator Operating in Low Magnetic Fields Using a Hybrid-TE₁₁ Mode