Review of Cold Cathode Research at the Air Force Research Laboratory

Shiffler, D.; Haworth, M.D.; Cartwright, Keith; Umstattd, R.; Ruebush, M.; Heidger, S.; LaCour, M.; Golby, K.; Sullivan, D. J.; Duselis, P.U.; Luginsland, J.W.

doi:10.1109/tps.2008.926227

Cited by 86 publications

(27 citation statements)

References 31 publications

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“…Therefore, these results suggest that Mo coating could effectively decrease cathode plasma expansion velocity of polymer velvet cathode because of the large mass of Mo, similar with the CsI-coated carbon fiber cathodes. 19,20,25,27 A simple simulation was performed by CHIPIC 3.0 with the FDTD algorithm, 28 assuming that cathode plasmas would expand toward the axial and radial direction with the same velocity and the expanded plasmas could be viewed as "new" cathode. When the fitted plasma expansion velocities of both two velvet cathodes were viewed as boundary conditions, the simulated cathode current with the diode voltage of 1.5 MV is 1.88 and 1.52 kA for uncoated and Mo-coated velvet cathodes, respectively, which is very close to the experimental values.…”

Section: Resultsmentioning

confidence: 99%

Modification of polymer velvet cathode via metallic Mo coating for enhancement of high-current electron emission performances

et al. 2013

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The effect of surface Mo coating on the high-current electron emission performances for polymer velvet cathode has been investigated in a diode with A-K gap of 11.5 cm by the combination of time-resolved electrical diagnostic and temporal pressure variation. Compared with uncoated polymer velvet cathode under the single-pulsed emission mode, the Mo-coated one shows lower outgassing levels ($0.40 Pa L), slower cathode plasma expansion velocity ($2.30 cm/ls), and higher emission stability as evidences by the change in cathode current, temporal pressure variation, and diode perveance. Moreover, after Mo coating, the emission consistency of the polymer velvet cathode between two adjacent pulses is significantly improved in double-pulsed emission mode with $500 ns interval between two pulses, which further confirms the effectiveness of Mo coating for enhancement of electron emission performance of polymer velvet cathodes. These results should be of interest to the high-repetitive high-power microwave systems with cold cathodes. V C 2013 AIP Publishing LLC. [http://dx.

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Section: Resultsmentioning

confidence: 99%

Modification of polymer velvet cathode via metallic Mo coating for enhancement of high-current electron emission performances

et al. 2013

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“…6,7 Further the ionization of the background gas probably results in beam breakup, mode competition, and so on, which would eventually cause the microwave pulse shortening. [8][9][10] Besides, the high-pressure background gas would also shorten the cathode lifetime and thus limit the maximum attainable pulse rep-rate. 11,12 As a result of these limitations, different materials have been used as alternatives of velvets in a variety of configurations.…”

Section: Introductionmentioning

confidence: 99%

“…Before an ideal material for cold cathodes is selected, the velvet may still be a choice. 10,16 Recently, researchers are still committing themselves to improve the vacuum condition for the traditional HPM tubes. 17,18 To realize further improvements of a rep-rate operated MILO with a velvet cathode, it is necessary to incorporate hard vacuum technology and eliminate significant sources of additional outgassing.…”

Section: Introductionmentioning

confidence: 99%

A distributed pumping model for a repetitive operated magnetically insulated transmission line oscillator

Xun

Zhang

Yang

et al. 2013

Journal of Applied Physics

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As one of the high power microwave sources, a magnetically insulated transmission line oscillator (MILO) works well in single shot mode. Recent interest has been focused on the repetition rate (rep-rate) operation of the device and it is important to improve the vacuum condition during the pulse bursts. In this paper, a dynamic pumping model for an L-band MILO was developed for the molecular movement and collision in the high-current vacuum diode chamber and the MILO tube on the basis of the Monte-Carlo method. According to the three dimension particle distribution, the idea of distributed pumping was proposed. In this way, another pump system close to the velvet cathode was introduced and located at the end of the MILO tube. Simulation results were verified through the experimental test carried out on a repetitive operated, high-voltage modulator, Torch-01 pulser. Results show that the distributed pumping can efficiently reduce the characteristic time of the pressure drop to one-fifth that of the single pumping. It is also indicated that the distributed pumping model has the potential for helping the MILO operate under rep-rate mode. V C 2013 AIP Publishing LLC. [http://dx.

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“…[1][2][3][4] The relativistic magnetron with diffraction output (MDO), [5][6][7][8][9][10][11] known as magnetron with axial radiation, is a promising device to be the most compact narrow band high power microwave (HPM) source. Compared with the traditional relativistic magnetron with radial extraction, the MDO not only succeeds the advantages such as simple structure and high efficiency but also has other special attractive features such as good azimuthal symmetry, compact magnetic coils, and directly radiating microwave in the axial direction.…”

Section: Introductionmentioning

confidence: 99%

Experimental demonstration of a compact high efficient relativistic magnetron with directly axial radiation

Liu

Shu

et al. 2012

Physics of Plasmas

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A compact relativistic magnetron with axial microwave radiation is experimentally investigated. Under the modified magnetic field distribution, only connecting a special horn antenna in the axial direction, the relativistic magnetron can stably radiate high power and high efficiency microwaves. The total length of the device is $0.3 m, and the volume is $0.014m 3 . In such working condition that the applied voltage is 539 kV and the magnetic field is $0.38 T, the output microwave power is $1.24 GW. Correspondingly, the total efficiency is about 34.1%. The radiating frequency is 2.35GHz, which is in agreement with the p mode frequency of the theoretical expectation.

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Review of Cold Cathode Research at the Air Force Research Laboratory

Cited by 86 publications

References 31 publications

Modification of polymer velvet cathode via metallic Mo coating for enhancement of high-current electron emission performances

Modification of polymer velvet cathode via metallic Mo coating for enhancement of high-current electron emission performances

A distributed pumping model for a repetitive operated magnetically insulated transmission line oscillator

Experimental demonstration of a compact high efficient relativistic magnetron with directly axial radiation

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