Boundary conditions for adsorbing-emitting electrodes in contact with seeded, dense plasmas

Adsorption and emission from boundary surfaces can profoundly alter the behavior of plasma-electrode systems, requiring a description that takes into account the physical characteristics of both the plasma and the surface. If the plasma is described in continuum terms, the surface properties enter through the specification of various species densities at the boundary, which strongly depend on the rates of emission of the respective species. Using the desorption rate expressions of Levine and Gyftopoulos for alkali metal coated metal surfaces, a method is proposed to determine boundary conditions for all species densities. The case of an equilibrium plasma confined between two plates is worked out in detail. The results suggest that ion densities could be very high near negatively biased boundaries, which in turn could lead to substantial field enhancement of thermionic electron emission. It is suggested that this mechanism might account for anomalously high currents observed in electrostatic probe studies.

[1]  R. Hoppmann.  Cold‐Electrode Characteristics in Shock‐Ionized Air Plasmas , 1968 .

[2]  J. Kalnavarns,et al.  The effect of surface emission on continuum electrostatic probe theory , 1968 .

[3]  P. D. Boer.  Flat plate probe for measuring ion density , 1968 .

[4]  A. Burke.  Electrical currents to a flat plate in supersonic ionized flow , 1968 .

[5]  C. Dewey.  A unified treatment of sheath problems in alkali plasma devices , 1967 .

[6]  A. Burke,et al.  A general theory of weakly ionized gas flows including compressibility and electron energy effects , 1967 .

[7]  H. Mckee.  Electrostatic probe theory and application in a high-temperature, collision-dominated, potassium-seeded argon plasma , 1967 .

[8]  Randolph J. Wolf,et al.  Electrode effects in a seeded plasma. , 1966 .

[9]  E. Wasserstrom,et al.  Kinetic Theory Approach to Electrostatic Probes , 1965 .

[10]  D. Turcotte,et al.  Electrode interactions in seeded combustion products , 1965 .

[11]  J. D. Levine,et al.  ADSORPTION PHYSICS OF METALS PARTIALLY COVERED BY METALLIC PARTICLES. PART III: EQUATIONS OF STATE AND ELECTRON EMISSION S-CURVES , 1964 .

[12]  Irvin Pollin.  Stagnation Point Langmuir Probe in a Shock Tube‐Theory and Measurements , 1964 .

[13]  J. D. Levine,et al.  Adsorption physics of metals partially covered by metallic particles. II desorption rates of atoms and ions , 1964 .

[14]  J. D. Levine,et al.  Adsorption physics of metallic surfaces partially covered by metallic particles. I atom and ion desorption energies , 1964 .

[15]  P. M. Chung.  Electrical Characteristics of Couette and Stagnation Boundary‐Layer Flows of Weakly Ionized Gases , 1964 .

[16]  J. D. Levine,et al.  Work Function Variation of Metals Coated by Metallic Films , 1962 .

[17]  J. B. Taylor.  THE EVAPORATION OF ATOMS, IONS AND ELECTRONS FROM CAESIUM FILMS ON TUNGSTEN , 1933 .