skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: ENERGY EXCHANGE IN THE HIGH-INTENSITY ARC PLASMA. TECHNICAL NOTE NO. 1. EFFECT OF FLUID TRANSPIRATION THROUGH THE ANODIC ARC BOUNDARY

Abstract

A basic discussion of arc phenomena is presented for the purposes of orientation and definition. Emphasis is placed on the distinction between low- intensity and high-intensity modes of arc operation. Following the preliminary discussion, the fundamental prenmises for the concept of a "fluid transpiration" arc are laid down. This concept relates to an arc discharge subject to the forced convection of a fluid medium, but differentiated from other systems of this type by the fact that the fluid is injected into the arc conduction zone via the anodic terminus through a porous anode structure. The postulated effectiveness criteria for this technique of arc heating require that the average pore size be less than the anode fall space thickness, that the transpiration surface be integrally congruent with the anodic discharge boundary, and that the injected gas particle flux density have the same order of magnitude as the opposing drift electron flux density within the anode sheath region. A two-phase experimental program is described, the first being concerned with the validation of the basic concept and the second with a study of intrinsic characteristics. The first group of experiments established the feasibility of fluid transpiration through the anodic arc boundary as amore » practical method of arc heating. Transition to a new mode of arc operation at a specific rate of fluid flow was demonstrated. The new mode exhibited general features similar to a Benck type high-intensity arc, but in some respects it is shown to be different. The second group of experiments detailed a number of unique properties for the technique of fluid transpiration through the anoden. Some evidence was obtained for an abnormally high degree of ionization in the plasma jet. Erosion tests on both porous graphite and tungsten demonstrated that steady state anode consumption as low as 10/sup, -6/ gms/sec are achievablen in an argon medium. The major cause of anode wear was found to be spalling of surface fragments due to arc ignition stresses. A very pure plasma jet, essentially free of electrode vapor, was generated for a wide range of gas flow ratens. Anode erosion using helium gas was found to be higher than that for argon, other things being equal. This is tentatively explained as an effect of relative atom-electron collision cross-sections ink. the anode sheath. Normalized specific enthalpiens between 1.0 and 5.0 k-cal/gm mole-kw at transfer efficiencies between 70 and 88.5% are reported. Probe experiments revealed an apparent smoothing effect for gas transpiration through the anode on the flow regime in the effiuent plasma. In addition an apprecnkable fraction (1/2 to 3/4) of the anode fall voltage was found to be detached from the anode surface by the gas flow, effectively dividing the fall space into two separate zones. These two zones are separated by an "anode dark space," characterized by the absence of Iuminosity and essentially zero voltage gradient. Finally, a new geometry, involving a truncated conical shell for the porous anode and a conical gas conduction zone, is shown to generate a region of exceptionally high energy density and provide a higher power input capability. (auth)« less

Authors:
; ; ;
Publication Date:
Research Org.:
Vitro Labs., West Orange, N.J.
OSTI Identifier:
4816820
Report Number(s):
AFOSR-860; VL-2143-10-0
NSA Number:
NSA-16-003528
DOE Contract Number:  
AF49(648)-477
Resource Type:
Technical Report
Resource Relation:
Other Information: Orig. Receipt Date: 31-DEC-62
Country of Publication:
United States
Language:
English
Subject:
PHYSICS; ANODES; ARGON; ATOMS; BEAMS; COATING; CROSS SECTIONS; DIFFUSION; EFFICIENCY; ELECTRIC ARCS; ELECTRODES; ELECTRONS; ENERGY; ENTHALPY; EROSION; EVAPORATION; FLUID FLOW; FLUIDS; GAS FLOW; GASES; GRAPHITE; HELIUM; IMPURITIES; INTERACTIONS; IONIZATION; MEASURED VALUES; PLASMA; POROSITY; SPUTTERING; STRESSES; SURFACES; TESTING; THERMODYNAMICS; TUNGSTEN; WEAR

Citation Formats

Sheer, C, Cooney, J A, Rothacker, D L, and Sileo, F R. ENERGY EXCHANGE IN THE HIGH-INTENSITY ARC PLASMA. TECHNICAL NOTE NO. 1. EFFECT OF FLUID TRANSPIRATION THROUGH THE ANODIC ARC BOUNDARY. United States: N. p., 1961. Web.
Sheer, C, Cooney, J A, Rothacker, D L, & Sileo, F R. ENERGY EXCHANGE IN THE HIGH-INTENSITY ARC PLASMA. TECHNICAL NOTE NO. 1. EFFECT OF FLUID TRANSPIRATION THROUGH THE ANODIC ARC BOUNDARY. United States.
Sheer, C, Cooney, J A, Rothacker, D L, and Sileo, F R. Fri . "ENERGY EXCHANGE IN THE HIGH-INTENSITY ARC PLASMA. TECHNICAL NOTE NO. 1. EFFECT OF FLUID TRANSPIRATION THROUGH THE ANODIC ARC BOUNDARY". United States.
@article{osti_4816820,
title = {ENERGY EXCHANGE IN THE HIGH-INTENSITY ARC PLASMA. TECHNICAL NOTE NO. 1. EFFECT OF FLUID TRANSPIRATION THROUGH THE ANODIC ARC BOUNDARY},
author = {Sheer, C and Cooney, J A and Rothacker, D L and Sileo, F R},
abstractNote = {A basic discussion of arc phenomena is presented for the purposes of orientation and definition. Emphasis is placed on the distinction between low- intensity and high-intensity modes of arc operation. Following the preliminary discussion, the fundamental prenmises for the concept of a "fluid transpiration" arc are laid down. This concept relates to an arc discharge subject to the forced convection of a fluid medium, but differentiated from other systems of this type by the fact that the fluid is injected into the arc conduction zone via the anodic terminus through a porous anode structure. The postulated effectiveness criteria for this technique of arc heating require that the average pore size be less than the anode fall space thickness, that the transpiration surface be integrally congruent with the anodic discharge boundary, and that the injected gas particle flux density have the same order of magnitude as the opposing drift electron flux density within the anode sheath region. A two-phase experimental program is described, the first being concerned with the validation of the basic concept and the second with a study of intrinsic characteristics. The first group of experiments established the feasibility of fluid transpiration through the anodic arc boundary as a practical method of arc heating. Transition to a new mode of arc operation at a specific rate of fluid flow was demonstrated. The new mode exhibited general features similar to a Benck type high-intensity arc, but in some respects it is shown to be different. The second group of experiments detailed a number of unique properties for the technique of fluid transpiration through the anoden. Some evidence was obtained for an abnormally high degree of ionization in the plasma jet. Erosion tests on both porous graphite and tungsten demonstrated that steady state anode consumption as low as 10/sup, -6/ gms/sec are achievablen in an argon medium. The major cause of anode wear was found to be spalling of surface fragments due to arc ignition stresses. A very pure plasma jet, essentially free of electrode vapor, was generated for a wide range of gas flow ratens. Anode erosion using helium gas was found to be higher than that for argon, other things being equal. This is tentatively explained as an effect of relative atom-electron collision cross-sections ink. the anode sheath. Normalized specific enthalpiens between 1.0 and 5.0 k-cal/gm mole-kw at transfer efficiencies between 70 and 88.5% are reported. Probe experiments revealed an apparent smoothing effect for gas transpiration through the anode on the flow regime in the effiuent plasma. In addition an apprecnkable fraction (1/2 to 3/4) of the anode fall voltage was found to be detached from the anode surface by the gas flow, effectively dividing the fall space into two separate zones. These two zones are separated by an "anode dark space," characterized by the absence of Iuminosity and essentially zero voltage gradient. Finally, a new geometry, involving a truncated conical shell for the porous anode and a conical gas conduction zone, is shown to generate a region of exceptionally high energy density and provide a higher power input capability. (auth)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1961},
month = {6}
}

Technical Report:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that may hold this item. Keep in mind that many technical reports are not cataloged in WorldCat.

Save / Share: