Investigations of time delays in microwave breakdown initiation

Dorozhkina, D. S.; Semenov, V. E.; Olsson, Torsten; Anderson, D.; Jordan, U.; Puech, J.; Lapierre, L.; Lisak, M.

doi:10.1063/1.2158696

Cited by 34 publications

(17 citation statements)

References 5 publications

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“…For pulsed applications without an obvious source of breakdown initiating electrons, the statistical waiting time can be on the same order as the avalanche time. 2 A generally valid estimation of the combined "statistical" delay time and the statistics of the "formative time" has been described for microwave breakdown for the time scale of tens of seconds. 2 These models can be adapted for pulsed discharges in which time-varying ionization rates are considered.…”

Section: Introductionmentioning

confidence: 99%

“…2 A generally valid estimation of the combined "statistical" delay time and the statistics of the "formative time" has been described for microwave breakdown for the time scale of tens of seconds. 2 These models can be adapted for pulsed discharges in which time-varying ionization rates are considered. The mathematical description, however, gets too complex for practical applications and a more pragmatic way is the direct simulation of the distributions using statistical sampling functions for random variables as they are available in, for instance, MATLAB™ or MAPLE™.…”

Section: Introductionmentioning

confidence: 99%

“…It has been described in some detail for volume geometries with uniform time independent electric field and well defined discharge length. 1,2 Traditionally, the analysis of breakdown statistics has involved graphing the statistical breakdown distribution as suggested by Laue, which is presented in Ref. 3.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the delay time distribution of high power microwave surface flashover

2011

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Characterizing and modeling the statistics associated with the initiation of gas breakdown has proven to be difficult due to a variety of rather unexplored phenomena involved. Experimental conditions for high power microwave window breakdown for pressures on the order of 100 to several 100 torr are complex: there are little to no naturally occurring free electrons in the breakdown region. The initial electron generation rate, from an external source, for example, is time dependent and so is the charge carrier amplification in the increasing radio frequency ͑RF͒ field amplitude with a rise time of 50 ns, which can be on the same order as the breakdown delay time. The probability of reaching a critical electron density within a given time period is composed of the statistical waiting time for the appearance of initiating electrons in the high-field region and the build-up of an avalanche with an inherent statistical distribution of the electron number. High power microwave breakdown and its delay time is of critical importance, since it limits the transmission through necessary windows, especially for high power, high altitude, low pressure applications. The delay time distribution of pulsed high power microwave surface flashover has been examined for nitrogen and argon as test gases for pressures ranging from 60 to 400 torr, with and without external UV illumination. A model has been developed for predicting the discharge delay time for these conditions. The results provide indications that field induced electron generation, other than standard field emission, plays a dominant role, which might be valid for other gas discharge types as well.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of the delay time distribution of high power microwave surface flashover

2011

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“…6 The stochastic nature of breakdown time delay was experimentally proven by Zuber,7 while its exponential distribution was theoretically confirmed by von Laue. 8 Besides dc electrical breakdowns of gases, when voltage pulses applied to the discharge gap are constant, [9][10][11] the time varying voltage pulses are also applied, such as linearly rising ramps, 12,13 triangular, 14,15 ac with linearly rising amplitude, 16,17 microwave, 18,19 etc. Unstable physical conditions in the experiment (e.g., cathode conditioning, wearing or aging) also affect the breakdown processes.…”

Section: Introductionmentioning

confidence: 99%

Multi-component non-stationary exponential distributions of the breakdown voltages and time delays in neon ramp breakdown experiments

Stamenković

Gocić

Marković

et al. 2011

Journal of Applied Physics

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The concept of physically based distributions used in studies concerning gas electrical breakdowns is introduced in this paper. The non-stationary exponential distribution of the breakdown voltages and time delays with time dependent distribution parameter is theoretically derived based on physical grounds starting from a binomial distribution for electron occurrence in the interelectrode gap. The experimental distributions of breakdown voltages Ub and time delays td are obtained by applying linearly rising (ramp) voltage pulses to the discharge tube with a hard galvanic layer of gold on the cathode and modeled by multi-component non-stationary exponential distribution, as well as by a Weibull distribution for the sake of comparison. In order to fit the experimental data, the multi-component voltage/time dependent distribution parameter YP is introduced, where Y is electron yield (number of generated electrons in the interelectrode gap per second), and P is breakdown probability (the probability of one electron to cause a breakdown). It is shown that multi-component non-stationary exponential distribution is suitable for modeling of the experimental data when time varying voltage pulses are applied to the discharge tube.

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“…The present analysis seeks to quantify otherwise qualitative speculations that deal with electron emission at localized, likely nanoscale, emission sites thought to accompany breakdown. Consequently, conditions existing in the microwave cavities (e.g., background pressure, microwave power, device dimensions, and so on [32,33]) are of secondary importance to the methods developed herein in spite of their generally paramount importance in the literature. Field emission electrons tunnel through surface barriers on femtosecond time scales, and the time duration between individual electron emission events (each of which contributes to Nottingham heating and cooling) from a 10 nm 2 area for current densities on the order of 10 8 A=cm 2 is 16 fs on average.…”

Section: Localized Heating Due To Emission and Its Relation To Brmentioning

confidence: 99%

Electron emission contributions to dark current and its relation to microscopic field enhancement and heating in accelerator structures

Jensen

Lau

Feldman

et al. 2008

Phys. Rev. ST Accel. Beams

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Analytically tractable models of thermal-field emission, field enhancement, and heating mechanisms (Nottingham and resistive) are developed and combined to make estimates of the fields and temperatures that accompany the development and growth of asperities. The relation of asperity dimensions to dark current is discussed in two experimentally motivated examples. The hypothetical relation of microscopic sources of dark current and heating to breakdown is discussed in the context of Nottingham and resistive heating. The latter are estimated using a general thermal-field methodology. A point-charge model is used to find field enhancement factors. Last, a thermal model is used to estimate the temperature dependence of the resistivity and thermal conductivity. Together, these models suggest that conditions can arise in which the temperature at the apex of an asperity can experience growth and contribute to melting or fracture (or both), and that Nottingham heating generally dominates the resistive heating term.

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Investigations of time delays in microwave breakdown initiation

Cited by 34 publications

References 5 publications

Investigation of the delay time distribution of high power microwave surface flashover

Investigation of the delay time distribution of high power microwave surface flashover

Multi-component non-stationary exponential distributions of the breakdown voltages and time delays in neon ramp breakdown experiments

Electron emission contributions to dark current and its relation to microscopic field enhancement and heating in accelerator structures

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