摘要:

Silver films were prepared by evaporation onto glass substrates held near 130 °C at different residual gas pressures (10−4to10−7Torr). Powder-pattern peaks of these films (thicknesses 2000 Å and 6000 Å) were measured with CuKα radiation at room temperature, and the profiles subjected to a Fourier analysis to determine particle size, strains, and faulting. Films prepared in poorer vacuum (10−4–10−6Torr) show small particle sizes (∼500Å), very small root-mean-squared strains (∼0.0005) and evidence for deformation stacking faults and micro-twinning. Lattice parameter measurements indicate the presence of internal strains in films heated to 250 °C for 2 h and measured at room temperature.

ISSN:0022-5355    

DOI:10.1116/1.1492444

出版商:American Vacuum Society    

年代:1966

数据来源: AIP

摘要:

H2and He discharges in a stellarator produce copious wall bombardment by the plasma ions. The reemission rate of the gas was measured for times of 0.06 to105see after bombardment. The rate was approximately proportional tot−0.6for He andt−0.75forH2. The reemission is also calculated assuming diffusion of the gas in the solid and taking into account the finite nonuniform initial distribution. It follows from the analysis that the rate is proportional tot−nwherenapproaches 0.5 or 1.5 as the ratio of reemission to bombarding time approaches zero or infinity.

ISSN:0022-5355    

DOI:10.1116/1.1492445

出版商:American Vacuum Society    

年代:1966

数据来源: AIP

摘要:

By use of a classical model, the phenomenon of trapping of a gas particle at the surface of a cold solid is investigated. The equation of motion is solved by the adoption of a semirepulsive potential of interaction and the equations determining the critical kinetic energy for trapping which is essential for the evaluation of the capture coefficient are obtained. These equations are simplified for the case that a gas particle collides on its own crystalline phase on account of the long “regression time” and the critical kinetic energy is thereby obtained. The regression time is the total time during which an initially free gas particle becomes trapped by the crystal surface before it is reevaporated again. It is long as compared to the period of lattice vibration.The cryopumping of condensable nonpolar gases is investigated. The existence of an adsorbed, mobile phase is taken into account in the derivation. The capture coefficients obtained forN2andCO2based on the geometric area of the cryosurface are quite satisfactory as compared with those derived from experimental data. Pressures as functions of flow rates were measured forCO2at a cryosurface temperature of 77.4 °K. The results are in good agreement with that calculated from the present simple theory.

ISSN:0022-5355    

DOI:10.1116/1.1492446

出版商:American Vacuum Society    

年代:1966

数据来源: AIP

摘要:

Measurements have been made of the nitrogen pressure ratio across a connecting stage as a function of the nitrogen exposure on the high-pressure side. The stage consisted of a titanium evaporator in a spherical glass bulb (8-cm diameter) which was connected to two glass ultra-high vacuum systems via short axially aligned tubes. When an unobstructed straight line path was allowed between the two systems, at least 99% of the transmitted gas was the direct “streaming” component which did not encounter the titanium surface. For the particular design reported here, the resulting pressure ratio was3.3×104. When the streaming path was obstructed, pressure ratios as high as3×107were measured. Saturation of the chemisorption on the evaporated titanium occurred at∼8×1014molecules percm2of macroscopic area. A single evaporator containing 0.12 g of titanium was able to deposit more than 300 films. Expressions are given from which the performance of other stages of similar design but of different dimensions can be estimated.

ISSN:0022-5355    

DOI:10.1116/1.1492447

出版商:American Vacuum Society    

年代:1966

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1492448

出版商:American Vacuum Society    

年代:1966

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1492450

出版商:American Vacuum Society    

年代:1966

数据来源: AIP