Sputter Ion Pump Research Articles

Gas evolution from sputter-ion pumps during baking: J.C. Riviere, 2nd Internat. Symp. residual gases in electron tubes, Milan, (March 1963), Nuovo Cimento (in press)

Gas evolution from sputter-ion pumps during baking: J.C. Riviere, 2nd Internat. Symp. residual gases in electron tubes, Milan, (March 1963), Nuovo Cimento (in press)

Gas evolution from sputter-ion pumps during baking

Gas evolution from sputter-ion pumps during baking

Investigations of titanium sheets for sputtering-ion pumps

Investigations of titanium sheets for sputtering-ion pumps

Investigations of titanium sheets for sputtering-ion pumps

Investigations of titanium sheets for sputtering-ion pumps

Pressure measurements above 1μ using commercial ionization gauges: R. Buser and J.J. Sullivan, Rev. Sci. Instrum., 33 (5), May 1962, 562–563

Performance characteristics and design of a hot-cathode magnetron getter-ion pump are described. The data on the ion current outputs (l+p ratio) for 2.5 cm and 4.5 cm cells are given as functions of the anode, repeller, and collector voltages and magnetic fieldstrength. The magnetic fieldstrength at cutoff varies from 40 to about 200 gauss. The optimum l+p ratio equals or exceeds the l/p ratio of single-cell as well as multi-cell Penning-type getter-ion pumps of the same size. A decrease of the l+/p ratio at low pressures does not occur. The sticking probability for argon is 0.75, which is about ten times the sticking probability obtained in sputter-ion pumps. Argon instability has not been observed, even after prolonged argon pumping at 3.10−5 torr.

Sensitivity of an Ion Pump Leak Detector

An analysis of the parameters governing the performance of a sputter-ion pump leak detector using oxygen or helium as the probe gas is presented. It is shown that the smallest detectable leak is proportional to the stability of the pump current and to the pressure. For optimum performance the pump control unit has to be voltage-stabilized. Expressions for the leak rate and minimum detectable leak in terms of the change of pump current are derived which predict an ultimate capability at least equal to that of conventional mass spectrometer leak detectors. This was confirmed experimentally.

Enhanced Hydrogen Pumping with Sputter-Ion Pumps

The physical processes which give rise to enhanced hydrogen pumping and anomalous differences between steady-state and dynamic pumping speeds are investigated. Observations suggest that two factors of dominant importance in the pumping of hydrogen are cathode surface conditions, which affect the rate at which incident molecular hydrogen is adsorbed, and permeability of the bulk material to hydrogen diffusion. Surface conditions are strongly affected by oxide films and layers of adsorbed gas, while permeability is influenced by temperature, crystal sizes and orientations, impurities and defects, and stresses in the metal. Results also show that a dramatic enhancement of pumping speed is observed after the pump cathodes are cleaned in vacuum by sputtering with argon ions. Thus, the initial value of the residual pumping speed suggests that with sufficiently clean cathode surfaces most of the hydrogen pumping can occur by direct molecular contact. (N.W.R.)

Physical processes in small titanium ion pumps

Experiments with small ion pumps in which titanium is continuously deposited are described. Two types were investigated, the first being a conventional thermionic ionisation gauge with titanium evaporating from a directly heated source in the envelope and the second a Penning type of discharge tube in which titanium was sputtered from the end plates. In the first type all the gases and vapours tested were pumped by ion burial and all except argon were also pumped by adsorption onto the already deposited titanium film and then covered by the arriving titanium. In addition the hot tungsten could combine chemically with oxygen and also convert hydrogen into the atomic form which was then able to diffuse into the titanium. Water vapour and organic vapours were also decomposed by the hot tungsten. In the Penning discharge pump the speed of pumping was constant for each gas over a wide range of pressures, and depended on the titanium sputtering rate and rate of adsorption of the various gases. It was found that appreciable desorption of pumped gases took place in the sputter-ion pump but could be made negligible in the evaporation-ion pump.

Radiant matter

<dm:abstracts xmlns:dm="http://www.elsevier.com/xml/dm/dtd"><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" view="all" class="author" id="aep-abstract-id5"><ce:section-title>Publisher Summary</ce:section-title><ce:abstract-sec view="all" id="aep-abstract-sec-id6"><ce:simple-para id="fsabs004" view="all">Various aspects of early plasma physics and chemistry are discussed in the chapter. Scientists used “frictional electricity” to study the chemistry in electric sparks and plasmas before 1800. After the invention of the voltaic battery in 1800 by A. Volta, the study of the chemistry in electric arcs rapidly developed. Since the mid 1800s, there have been a number of studies of glow discharges and the spectral emission from the glows. The first glow (gas) discharge “vacuum tube” was made by M. Faraday in 1838, using brass electrodes and a vacuum of approximately 2 Torr. In the late 1930s, an electron trap, which used a combination of electric and magnetic fields parallel to the surface called the “Penning effect,” was used to enhance the plasmas near the surface in sputtering from cylindrical-hollow (inverted) magnetrons and cylindrical-post magnetrons. The Penning effect was incorporated into a number of other applications, such as vacuum gauges, sputter-ion pumps, and microwave tubes. The time and rate of diffusion of ions to a surface determines the lifetime (decay time) of the plasma after the power to sustain the plasma is cutoff. The lifetime of the plasma can be extended by using a magnetic field to confine the plasma away from surfaces.</ce:simple-para></ce:abstract-sec></ce:abstract></dm:abstracts>