dorsal/arxiv
View SchemaRelation between space charge limited current and power loss in open drift tubes
| Authors | Debabrata Biswas, Raghwendra Kumar |
|---|---|
| Categories | |
| ArXiv ID | physics/0603234 |
| URL | https://arxiv.org/abs/physics/0603234 |
| DOI | 10.1063/1.2218820 |
| Journal | Physics of Plasmas 13 (2006) 073101 |
Abstract
Drift space is a region free from externally applied fields. It is an important part of many devices involving charged particle beams. The space charge effect imposes a limit on the current that can be transported through a drift space. A reasonable estimate of the space charge limited current density (J_{SCL}^{c}) in 'closed' drift tubes can be obtained from electrostatic considerations despite the fact that charge particle transport results in electromagnetic radiation. We deal here with the situation where the drift tube is 'open' to electromagnetic radiation, for instance due to the presence of a dielectric window. In such cases, electromagnetic radiation leaks out of the window which results in a decrease in the average kinetic energy of electrons. If the injected current density is much lower than J_{SCL}^{c}, power loss does not result in a change in the transmitted current. As the injected current density is increased, power loss increases and at a critical value lower than J_{SCL}^{c}, reflection of electrons begins to occur. We also show that the lowering of the space charge limited current on account of power loss can be incorporated in the standard electrostatic picture by introducing an effective voltage for the collection plate.
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"abstract": "Drift space is a region free from externally applied fields. It is an\nimportant part of many devices involving charged particle beams. The space\ncharge effect imposes a limit on the current that can be transported through a\ndrift space. A reasonable estimate of the space charge limited current density\n(J_{SCL}^{c}) in \u0027closed\u0027 drift tubes can be obtained from electrostatic\nconsiderations despite the fact that charge particle transport results in\nelectromagnetic radiation. We deal here with the situation where the drift tube\nis \u0027open\u0027 to electromagnetic radiation, for instance due to the presence of a\ndielectric window. In such cases, electromagnetic radiation leaks out of the\nwindow which results in a decrease in the average kinetic energy of electrons.\nIf the injected current density is much lower than J_{SCL}^{c}, power loss does\nnot result in a change in the transmitted current. As the injected current\ndensity is increased, power loss increases and at a critical value lower than\nJ_{SCL}^{c}, reflection of electrons begins to occur. We also show that the\nlowering of the space charge limited current on account of power loss can be\nincorporated in the standard electrostatic picture by introducing an effective\nvoltage for the collection plate.",
"arxiv_id": "physics/0603234",
"authors": [
"Debabrata Biswas",
"Raghwendra Kumar"
],
"categories": [
"physics.plasm-ph"
],
"doi": "10.1063/1.2218820",
"journal_ref": "Physics of Plasmas 13 (2006) 073101",
"title": "Relation between space charge limited current and power loss in open drift tubes",
"url": "https://arxiv.org/abs/physics/0603234"
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