Explosive emission and gap closure from a relativistic electron beam diode

Coleman, J. E.; Moir, D.C.; Ekdahl, C.A.; Johnson, J. B.; McCuistian, B.T.; Crawford, M.

doi:10.1109/ppc.2013.6627454

Cited by 5 publications

(3 citation statements)

References 19 publications

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“…Using our simulation model, a relationship is built between the current and the voltage for each diode geometry, without taking the plasma motion into account. This approach appears to be more accurate than an analytical one because no assumption is made on the relationship between current density and voltage [29].…”

Section: Diode Resultsmentioning

confidence: 99%

High power electron diode for linear induction accelerator at a flash radiographic facility

Plewa

Bernigaud

Barnes

et al. 2018

Phys. Rev. Accel. Beams

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We investigated a new cathode design and beam transport with the EPURE axis-1 injector in order to increase the beam characteristics at 3.8 MeV, 80 ns FWHM from the 2.0 kA nominal current to 2.6 kA corresponding to an average current density of 82 A=cm 2 . Such current increase is highly desirable for improving the x-ray dose and hence radiographic performances. To achieve this, a time-dependent model based on the particle-in-cell method was developed in order to simulate the injector. Using results from calculations based on this model, a 17.2 cm AK gap diode with a larger radius cathode (3.175 cm) was designed, manufactured and tested. Experimental and calculated currents and emittances are qualitatively compared. The study provides a detailed understanding of the beam dynamics inside this type of high current, high energy injector.

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Section: Diode Resultsmentioning

confidence: 99%

High power electron diode for linear induction accelerator at a flash radiographic facility

Plewa

Bernigaud

Barnes

et al. 2018

Phys. Rev. Accel. Beams

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“…Initial emission area for cathode is related to REB uniformity and plasma expansion velocity is related to the duration of electron beam current, provided applied voltage pulse duration is quite large [17]. These calculations, however, are entirely different for very high-voltage diodes, that is, relativistic cases (>500 keV) [18]. This paper presents the experimental study of timedependent diode voltage and current waveform for various cathode materials namely graphite, stainless steel (SS), and red polymer velvet cathode [19].…”

Section: Introductionmentioning

confidence: 99%

Explosive Emission Properties of Cathode Materials in Relativistic Electron Beam Generation

Chandra¹,

Roy²,

Kalyanasundaram³

et al. 2014

IEEE Trans. Plasma Sci.

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Relativistic electron beam generation studies have been carried out in LIA-400 system through explosive electron emission for various cathode materials. This paper presents the emission properties of different cathode materials at peak diode voltages varying from 10 to 220 kV and at peak current levels from 0.5 to 2.2 kA in a single pulse duration of 160-180 ns. The cathode materials used are graphite, stainless steel, and red polymer velvet. The perveance data calculated from experimental waveforms are compared with 1-D Child Langmuir formula to obtain the cathode plasma expansion velocity for various cathode materials. Various diode parameters are subject to shot to shot variation analysis. Velvet cathode proves to be the best electron emitter because of its lower plasma expansion velocity and least shot to shot variability.Index Terms-Electron beam applications, electron beams, electron emission, electron sources, plasma devices, pulse power systems.

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“…CsI doped carbon velvet has also been examined at low resolution indicating 3 x 10 4 pulses were required to measure H [16]. The first axis of the Dual-Axis Radiography for Hydrodynamic Testing (DARHT) facility [25,26] is characterizing the photon spectrum generated in the diode in motivation to gain a better understanding of the electron beam generation through the use of a cold cathode, including the beam and plasma dynamics, and beam emittance. In addition there is a motivation to use of this cathode technology for longer (~ s) pulsed and multi-pulsed operations and continue to develop improved high brightness (B = J/ ) cold cathodes.…”

Section: Introductionmentioning

confidence: 99%

Characterizing the photon spectrum in the DARHT Axis-I diode

Coleman¹,

Johnson²,

McCuistian³

et al. 2014

2014 IEEE 41st International Conference on Plasma Sciences (ICOPS) Held With 2014 IEEE International Conference on High-Power P

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An array of photon diagnostics have been deployed on a high power relativistic electron beam diode. Surface flashover of a carbon fiber velvet cathode generates a discharge from which electrons are accelerated through a 17.8 cm diode. This discharge is assumed to be a hydrocarbon mixture. A small portion of the off energy electrons (1-3 MeV) accelerated during the rise and fall of the 80 ns FWHM pulse impact the beam pipe and generate a Bremsstrahlung spectrum of 0.1-3 MeV photons. The principal objective of these experiments is to quantify the dynamics of the hard X-ray and -ray flux generated in the diode region, in addition to quantifying dynamics of the visible photons generated, and the ion species of the surface discharge on the velvet cathode. A qualitative comparison of different diagnostic results are presented, which include time resolved measurements with X-ray PIN diodes, a PMT, and CCD images. In addition initial visible spectroscopy measurements will also be presented.

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Explosive emission and gap closure from a relativistic electron beam diode

Cited by 5 publications

References 19 publications

High power electron diode for linear induction accelerator at a flash radiographic facility

High power electron diode for linear induction accelerator at a flash radiographic facility

Explosive Emission Properties of Cathode Materials in Relativistic Electron Beam Generation

Characterizing the photon spectrum in the DARHT Axis-I diode

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