Buffer gas

About: Buffer gas is a research topic. Over the lifetime, 3565 publications have been published within this topic receiving 47283 citations.

Electron disappearance in pulse irradiated fluorocarbon gases

Abstract: Rate constants for electron attachment to some highly reactive fluorocarbon gases have been determined by microwave conductometric methods. Initial ionization of the gas was by pulse radiolysis with 2.8 MeV electrons. To facilitate measurements on very reactive compounds a method has been developed which is applicable when the electron half‐life is < 1 μsec. This method uses the amplitude of the steady‐state response of the detector during the pulse and the rate of production of electrons based on measurements on the nonattaching buffer gas alone. This steady‐state method was tested on mixtures of CF2Cl2 or SF6 in C3H8 and was shown to agree with direct measurements of the decay of the electron concentration. With propane as the buffer gas the method is applicable where the electron half‐life is greater than about 0.5 μsec at 1 torr total pressure. At higher pressures of attaching gas decreases in apparent rate constant were observed which could be attributed to electron reaction before complete thermalization. Values for thermal attachment rate constants (cm3 molecule−1 · sec−1) at 25 °C found in this work are 1.3 × 10−9 for CF2Cl2; 1.2 × 10−8 for cyclo‐C4F8, 1.4 × 10−7 for cyclo‐C4F6, and 4.9 × 10−8 for C4F8‐2. In comparison to these values that for cyclo‐C3F6 was determined to be < 3 × 10−14. Perfluoropropylene was found to undergo a transition from three‐ to two‐body behavior at high pressures of buffer gas, and the rate constant values imply a negative ion lifetime near 1 μsec. The limiting value of the two‐body rate constant was found to be 3 × 10−10 cm3 molecule−1 · sec−1.

Excimer laser output control device

Abstract: An excimer laser including a discharge chamber containing a mixture of halogen, rare gas and buffer gas uses two gas sources to replenish the halogen in the discharge chamber while maintaining the concentrations of all the gases at the optimum levels. One of the gas sources, source A, contains a mixture of the rare gas and the buffer gas in optimum concentrations. The other gas source, source B, contains both the rare gas and the buffer gas, in optimum relative concentrations, and also the halogen, in a concentration which is greater than optimum. As the laser operates and the gain of the laser decreases due to halogen depletion, gas from source B is injected into the discharge chamber to raise the halogen concentration. Gas is then released from the chamber to reduce the chamber pressure to the original level. When halogen replenishment does not suffice to restore the laser gain, due to the build-up of contaminants in the chamber, a portion of chamber gas is released and it is replenished with fresh gas from both sources in proportions adequate to provide optimum concentrations of the various gases.

Process for preparing finely-divided refractory powders

Abstract: Helical flow of hot plasma gas, e.g., hydrogen gas, produced by a gas vortex stabilized plasma arc is cancelled by introducing attenuating gas, e.g., hydrogen gas, into the hot plasma gas in a manner such that the attenuating gas assumes a vortical direction opposite to the helical flow of the hot plasma gas. The resulting gas stream is well-collimated. The well-collimated plasma gas stream is used in the preparation of finely-divided refractory metal and metalloid carbides, borides, nitrides, silicides and sulfides. Reactants for the preparation of the aforementioned refractory powders are introduced into the collimated plasma gas stream. The reaction is conducted in the gas phase within a reactor and solid, finely-divided refractory powder removed from the reactor.

Flue gas desulfurization

Abstract: A process and apparatus for removing sulfur oxide from combustion gas to form Na2SO4 and for reducing the harmful effects of Na2SO4 on auxiliary heat exchangers in which a sodium compound is injected into the hot combustion gas forming liquid Na2SO4 in a gas-gas reaction and the resultant gas containing Na2SO4 is cooled to below about 1150°K to form particles of Na2SO4 prior to contact with at least one heat exchanger with the cooling being provided by the recycling of combustion gas from a cooled zone downstream from the introduction of the cooling gas.

Photolithographic mask repair system

Abstract: A method and device are provided to accomplish laser driven pyrolytic, photolytic and photoactivativation process requiring controlled atmosphere without the use of gas tight cells. A method and device are provided to correct clear faults on a photo-lithographic mask by metallic deposition on the mask at standard temperature and pressure. The deposition is formed by the pyrolytic decomposition of an organometallic gas mixture which may include chromium and molybdenum hexacarbonyls, and a buffer gas. The decomposition is done utilizing a laser beam. The device may be incorporated into a system which has other members used to correct opaque faults in the same mask.