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Different operation regimes of cylindrical triode-type electron accelerator studied by PIC code simulations

Published online by Cambridge University Press:  14 December 2016

R. Fetzer ,
W. An ,
A. Weisenburger  and
G. Mueller
R. Fetzer*
Affiliation:
Karlsruhe Institute of Technology, Institute for Pulsed Power and Microwave Technology, P.O. Box 3640, 76021 Karlsruhe, Germany
W. An
Affiliation:
Karlsruhe Institute of Technology, Institute for Pulsed Power and Microwave Technology, P.O. Box 3640, 76021 Karlsruhe, Germany
A. Weisenburger
Affiliation:
Karlsruhe Institute of Technology, Institute for Pulsed Power and Microwave Technology, P.O. Box 3640, 76021 Karlsruhe, Germany
G. Mueller
Affiliation:
Karlsruhe Institute of Technology, Institute for Pulsed Power and Microwave Technology, P.O. Box 3640, 76021 Karlsruhe, Germany
*
Address correspondence and reprint requests to: R. Fetzer, Karlsruhe Institute of Technology, Institute for Pulsed Power and Microwave Technology, P.O. Box 3640, 76021 Karlsruhe, Germany. E-mail: renate.fetzer@kit.edu
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Abstract

The performance of the converging electron beam generated in cylindrical triodes is systematically studied by particle-in-cell code simulations. Depending on the cathode and grid potentials applied, different operation regimes are identified. For low voltages between cathode and grid, laminar flow and homogeneous beam energy density at the target (anode) is obtained. This applies both to the case of unipolar electron flow and to bipolar flow with counter-streaming ions. Hereby, the electron emission current is enhanced by about 50% for bipolar flow compared with unipolar flow. A further increase by about 20% is obtained when electron backscattering at the target is enhanced due to a change of target material from aluminum to tungsten. For cathode-grid voltages exceeding a critical value, laminar flow is replaced by non-laminar flow regimes. For unipolar electron beams, a virtual cathode forms between grid and target, which leads to an inhomogeneous power density at the target. For the specific geometry investigated and the cathode potential fixed at −120 kV, the cathode-grid voltage threshold for the formation of the virtual cathode is ~32 kV for Al targets and ~28 kV for W targets. For bipolar flow, the laminar flow regime already ends at cathode-grid voltages of ~23 kV (Al target) and ~20 kV (W target), respectively, and is replaced by magnetic insulation at the beam edge. For increasing cathode-grid voltage, the magnetically insulated region extends until beam pinching occurs.

Keywords

Cylindrical triodeOperation regimesPIC code simulationsPulsed electron beam
Type
Research Article
Information
Laser and Particle Beams , Volume 35 , Issue 1 , March 2017 , pp. 33 - 41
Copyright
Copyright © Cambridge University Press 2016 

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References

REFERENCES

Altsybeyev, V., Engelko, V., Ovsyannikov, A., Ovsyannikov, D., Ponomarev, V., Fetzer, R. & Mueller, G. (2016). Numerical simulation of a triode source of intense radial converging electron beam. J. Appl. Phys. 120, 143301.CrossRefGoogle Scholar
An, W., Engelko, V., Mueller, G. & Weisenburger, A. (2009). Optical investigation of plasma formation process by interaction of intense electron beams with metallic targets. Acta Phys. Pol. A 115, 1183–1185.Google Scholar
Archiopoli, U.C., Mingolo, N. & Mingolo, N. (2008). Generation of hardened steel surfaces with adjustable roughness by means of a pulsed electron beam. Surf. Coat. Technol. 202, 5982–5990.Google Scholar
Batrakov, A.V., Markov, A.B., Ozur, G.E., Proskurovsky, D.I. & Rotshtein, V.P. (2008). Surface alloying of metallic substrates with pre-deposited films through a pulsed electron-beam mixing. Eur. Phys. J. Appl. Phys. 43, 283–288.Google Scholar
Chen, X., Dickens, J., Hatfield, L.L., Choi, E.-H. & Kristiansen, M. (2004). Approximate analytical solutions for the space-charge-limited current in one-dimensional and two-dimensional cylindrical diodes. Phys. Plasmas 11, 3278–3283.Google Scholar
Child, C.D. (1911). Discharge from hot CaO. Phys. Rev. 32, 492–511.Google Scholar
Engelko, V. (2014). Source of radial converging electron beam for modification of long-length cylindrical targets. 10th International Vacuum Electron Sources Conference (IVESC), 2014 – Proceedings. DOI: 10.1109/IVESC.2014.6891971.Google Scholar
Engelko, V., Kuznetsov, V. & Mueller, G. (2009). Electron source of triode type with radial converging electron flow for irradiation of cylindrical targets. J. Appl. Phys. 105, 023305.Google Scholar
Engelko, V., Kuznetsov, V., Viazmenova, G., Mueller, G. & Bluhm, H. (2000). Influence of electrons reflected from a target on the operation of triode-type electron sources. J. Appl. Phys. 88, 3879–3888.Google Scholar
Engelko, V. & Mueller, G. (2005). Formation of plasma and ion flux on a target, irradiated by an intense electron beam. J. Appl. Phys. 98, 013303.Google Scholar
Fetzer, R., An, W., Weisenburger, A. & Mueller, G. (2013). Surface layer dynamics during e-beam treatment. IEEE Trans. Plasma Sci. 41, 2858–2862.Google Scholar
Fetzer, R., Weisenburger, A., Jianu, A. & Mueller, G. (2012). Oxide scale formation of modified FeCrAl coatings exposed to liquid lead. Corrosion Sci. 55, 213–218.Google Scholar
Goplen, B., Ludeking, L., Smithe, D. & Warren, G. (1995). User-configurable MAGIC for electromagnetic PIC calculations. Computer Phys. Commun. 87, 54–86; http://www.magictoolsuite.com/magic/description.html Google Scholar
Langmuir, I. (1913). The effect of space charge and residual gases on thermionic currents in high vacuum. Phys. Rev. 2, 450–486.Google Scholar
Langmuir, I. & Blodgett, K.B. (1923). Currents limited by space charge between coaxial cylinders. Phys. Rev. 22, 347–356.Google Scholar
Miller, R.B. (1982). An Introduction to the Physics of Intense Charged Particle Beams. New York: Plenum.Google Scholar
Mueller, G., Engelko, V., Weisenburger, A. & Heinzel, A. (2005). Surface alloying by pulsed intense electron beams. Vacuum 77, 469–474.Google Scholar
Mueller, G., Schumacher, G. & Strauss, D. (1998). Oxide scale growth on MCrAlY coatings after pulsed electron beam treatment. Surf. Coat. Technol. 108–109, 43–47.Google Scholar
Mueller, G., Schumacher, G. & Zimmermann, F. (2000). Investigation on oxygen controlled liquid lead corrosion of surface treated steels. J. Nucl. Mater. 278, 85–95.Google Scholar
Oliver, B.V., Genoni, T.C., Rose, D.V. & Welch, D.R. (2001). Space-charge limited currents in coaxial diodes with electron backscatter. J. Appl. Phys. 90, 4951–4956.CrossRefGoogle Scholar
Proskurovsky, D.I., Rotshtein, V.P., Ozur, G.E., Markov, A.B., Nazarov, D.S., Shulov, V.A., Ivanov, Yu.F. & Buchheit, R.G. (1998). Pulsed electron-beam technology for surface modification of metallic materials. J. Vac. Sci. Technol. A 16, 2480–2488.Google Scholar
Weisenburger, A., Jianu, A., An, W., Fetzer, R., Del Giacco, M., Heinzel, A., Mueller, G., Markov, V.G. & Kasthanov, A.D. (2012). Creep, creep-rupture tests of Al-surface-alloyed T91 steel in liquid lead bismuth at 500 and 550 °C. J. Nucl. Mater. 431, 77–84.Google Scholar
Zou, J.X., Zhang, K.M., Hao, S.Z., Dong, C. & Grosdidier, T. (2010). Mechanisms of hardening, wear and corrosion improvement of 316L stainless steel by low energy high current pulsed electron beam surface treatment. Thin Solid Films 519, 1404–1415.CrossRefGoogle Scholar