摘要:

The sorption kinetics of nitrogen at pressures of1×10−5to1×10−3 Torron titanium foil was studied ill the range 600 °–800 °C, by using an ultrahigh vacuum microbalance. In the similar way to oxygen, the rate law of nitrogen sorption was separable into two types, i.e., the linear rate law in the initial period and the parabolic rate law in the latter period. The linear rate law was obeyed for shorter times as the nitrogen pressure and the reaction temperature increased. In the initial linear part, the sorption rate was proportional to the nitrogen pressure at each temperature, which showed the linear sorption to be controlled by the rate of arrival. The sticking probability and pumping speed per unit area(cm2)for nitrogen were constant with change of nitrogen pressure, e.g., at 800 °C, 0.0045 for sticking probability and0.098 (liter sec−1)for pumping speed. The transtion in the sorption rate laws and critical pressure of nitrogen for the transition are discussed on the basis of a diffusion theory.

ISSN:0022-5355    

DOI:10.1116/1.1316680

出版商:American Vacuum Society    

年代:1972

数据来源: AIP

摘要:

The rate of the hydrogen-titanium reaction has been measured at 75 °C and at hydrogen pressures between10−4and10−2 Torr. Thin films of titanium were deposited on Kovar substrates at room temperature and mechanically transferred in vacuum to a reaction chamber where the rate of the reaction was measured using the flow technique. The rate of the reaction is linearly dependent on the hydrogen pressure and independent of the quantity of gas absorbed for hydrogen to titanium atomic ratios between 0.15 and 1.5.

ISSN:0022-5355    

DOI:10.1116/1.1316681

出版商:American Vacuum Society    

年代:1972

数据来源: AIP

摘要:

A new radiant heated sublimator is described which employs an approximately spherical shell of titanium enclosing a tungsten filament heater. The sublimator is relatively simple in construction and can dispense ∼37 g of titanium at sublimation rates up to 0.5 g/h. The sublimation rate at a given power input remains relatively constant throughout the life of the sublimator, making it very simple and reliable to operate. Comparative experiments are described with both spherical and cylindrical sublimators which illustrate the effect of various designs on the sublimation rate versus power and time characteristics. The operating characteristics of this device are discussed relative to other sublimation sources in common use in the field of titanium sublimation pumping.

ISSN:0022-5355    

DOI:10.1116/1.1316682

出版商:American Vacuum Society    

年代:1972

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1316683

出版商:American Vacuum Society    

年代:1972

数据来源: AIP

摘要:

A molecular beam at temperatureTGwas impinged onto the surface of a copper block held at temperatureTS. The fraction of molecules reflected was 1−γ, where γ is the condensation coefficient. Of the reflected molecules, a fixed fraction was condensed on the surface of a quartz crystal microbalance. Precision measurements of the mass flux onto the microbalance gave a direct determination of the rate of reflection of molecules from the surface of the copper block. This information, combined with the known flux of molecules onto the copper block, gave high precision (∼0.01%) values of γ. ForCO2condensing on a film of solidCO2, γ>0.96 whenTS≤83 KandTS=274 K. Water molecules condensing on water ice films give γ≥0.99 whenTS≤150 KandTG=273 K. Values of γ forCO2were found to depend onTS,TGand the molecular beam intensityṅCB. The range through whichṅCBvaried was1.5×1014to1.5×1016 molecules cm−2⋅sec−1.

ISSN:0022-5355    

DOI:10.1116/1.1316684

出版商:American Vacuum Society    

年代:1972

数据来源: AIP