THE ROLE OF ADSORPTION ENERGY IN THE IONIZATION OF ATOMS ON A METAL SURFACE (in Russian)
The potassium ion current I (atoms/cm/sup 2/) emitted from the (001) crystal face of a tungsten thermionic emitter was measured as a function of the emitter threshold temperature over a range of 1250 to 1500 deg K. The rolling process used to make the tungsten ribbon 0.2 mm thick had oriented the crystals. A 0.2 mm thick tantalum ribbon served as the collector. The results could be expressed by the equation T = 13,600/(8 -- log I). A theory relating T and I with an adsorption energy lambda , the ionization coefficient for the bare metal, and the fractional coverage theta is derived for small theta by postulating that the adsorbed atoms sit a distance delta from the reflecting surface of the metal with an effective charge e' (which are determined from electrostatic considerations). The adsorption energy is found by summing over the quadrupoles formed by the adsorbed ions. For potassium adsorbed on tungsten, lambda = 2.2 ev. If it is assumed that the heat of evaporation for potassium is 0.88 ev, the evaporator temperature T/sub evap/ is related to the threshold temperature of the emitter T as follows: T == 3.3 T/sub evap/. (TTT)
- Research Organization:
- All-Union Inst. for the Study of Monocrystals, Scintillating Materials, and Ultrapure Chemicals, Academy of Sciences, USSR
- NSA Number:
- NSA-18-010833
- OSTI ID:
- 4078545
- Journal Information:
- Doklady Akademii Nauk SSSR (U.S.S.R.) English translation currently published in a number of subject-oriented journals, Vol. Vol: 153; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- Russian
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