Shot to shot variation in perveance of the explosive emission electron beam diode

Roy, Amitava; Menon, R.; Singh, Sandeep; Kulkarni, Manasi; Saroj, P. C.; Nagesh, K. V.; Mittal, K. C.; Chakravarthy, D. P.

doi:10.1063/1.3097903

Cited by 19 publications

(21 citation statements)

References 11 publications

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“…But in the case of a planar diode the initial emission area increases with the accelerating gap. 11 In our previous experiments with 50 mm diameter planar graphite cathode and 1.3 cm AK gap the maximum diode voltage obtained was only 185 kV with a very high current of 43.5 kA. 14 A very fast gap closer has been observed in this planar diode experiment.…”

Section: Experimental Results and Analysismentioning

confidence: 62%

“…Also it may so happen that the full cathode fails to participate in the emission process leading to a current less than that predicted by the space-charge law. 11 Therefore, it is very difficult to predict the diode current unless we know the cathode and anode plasma expansion velocity and the effective emission area. Time and space resolved optical measurements are to be carried out to measure the plasma velocity and the effective emission area.…”

Section: Introductionmentioning

confidence: 99%

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Electron beam current in high power cylindrical diode

et al. 2010

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Intense electron beam generation studies were carried out in high power cylindrical diode to investigate the effect of the accelerating gap and diode voltage on the electron beam current. The diode voltage has been varied from 130 to 356 kV, whereas the current density has been varied from 87 to 391 A/cm2 with 100 ns pulse duration. The experimentally obtained electron beam current in the cylindrical diode has been compared with the Langmuir–Blodgett law. It was found that the diode current can be explained by a model of anode and cathode plasma expanding toward each other. However, the diode voltage and current do not follow the bipolar space-charge limited flow model. It was also found that initially only a part of the cathode take part in the emission process. The plasma expands at 4.2 cm/μs for 1.7 cm anode-cathode gap and the plasma velocity decreases for smaller gaps. The electrode plasma expansion velocity of the cylindrical diode is much smaller as compared with the planar diode for the same accelerating gap and diode voltage. Therefore, much higher voltage can be obtained for the cylindrical diodes as compared with the planar diodes for the same accelerating gap.

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Section: Experimental Results and Analysismentioning

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Electron beam current in high power cylindrical diode

et al. 2010

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“…The results of experimental investigations on shot-to-shot variation in the perveance of a planar electron diode with a graphite explosive-emission cathode were reported by Roy et al 6 It was shown that the perveance shot-to-shot variation increases from 24% at t = 50 ns, and up to 60% at t = 90 ns. In this case the variation was explained by variations in the effective emission area of the cathode and anodecathode (A-K) gap spacing due to the expending plasma, where the expansion was both radial and axial.…”

Section: Introductionmentioning

confidence: 77%

Shot-to-shot reproducibility of a self-magnetically insulated ion diode

Pushkarev

Isakova

Khailov

2012

Review of Scientific Instruments

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In this paper we present the analysis of shot to shot reproducibility of the ion beam which is formed by a self-magnetically insulated ion diode with an explosive emission graphite cathode. The experiments were carried out with the TEMP-4M accelerator operating in double-pulse mode: the first pulse is of negative polarity (300-500 ns, 100-150 kV), and this is followed by a second pulse of positive polarity (150 ns, 250-300 kV). The ion current density was 10-70 A/cm(2) depending on the diode geometry. The beam was composed from carbon ions (80%-85%) and protons. It was found that shot to shot variation in the ion current density was about 35%-40%, whilst the diode voltage and current were comparatively stable with the variation limited to no more than 10%. It was shown that focusing of the ion beam can improve the stability of the ion current generation and reduces the variation to 18%-20%. In order to find out the reason for the shot-to-shot variation in ion current density we examined the statistical correlation between the current density of the accelerated beam and other measured characteristics of the diode, such as the accelerating voltage, total current, and first pulse duration. The correlation between the ion current density measured simultaneously at different positions within the cross-section of the beam was also investigated. It was shown that the shot-to-shot variation in ion current density is mainly attributed to the variation in the density of electrons diffusing from the drift region into the A-K gap.

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“…During the last decades, several statistical methods have been applied to electromagnetic [13]- [15], mechanical problems [16], and Vircator studies [17]- [20]. From crude Monte Carlo (MC) [21], [22] (known as a brute force technique) to Polynomial Chaos [23], [24], it has been shown how the confidence level could be assessed when dealing with random variables [25].…”

Section: Introductionmentioning

confidence: 99%