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Showing papers on "Buffer gas published in 1982"


Journal ArticleDOI
TL;DR: In this article, a simulation code including the Boltzmann equation which describes the kinetics of the self-sustained discharge XeCl laser is developed, and the performances of four different gas mixtures, HCl/Xe/Ne, Hcl/ Xe/He, F2/Kr/Ne and F2/(Kr)/He are compared under the same conditions, and buffer gas effect is discussed in detail.
Abstract: A simulation code including the Boltzmann equation which describes the kinetics of the self-sustained discharge XeCl laser is developed. The performances of four different gas mixtures, HCl/Xe/Ne, HCl/Xe/He, F2/Kr/Ne and F2/Kr/He are compared under the same conditions, and the buffer gas effect is discussed in detail. The HCl/Xe/Ne system shows the best performance. With the Ne buffer gas, the elastic collision loss is remarkably small, whereas the electric circuit loss is large owing to the low discharge resistance. The results on the variation of the input energy and total pressure are qualitatively consistent with the experimental results. Useful knowledge on the design of efficient XeCl lasers is obtained.

80 citations


Journal ArticleDOI
TL;DR: In this article, a UV-preionized rare-gas halide laser with a large aperture to 7×7 cm2 and active volume of 4 l has been operated at a high pressure regime of 5 atm.
Abstract: A UV‐preionized rare‐gas halide laser with a large aperture to 7×7 cm2 and active volume of 4 l has been operated at a high pressure regime of 5 atm. Beam profile measurements at the midplane between electrodes have shown the beam widths of 7 cm at a half‐energy density both in KrF and XeCl. The improvement in discharge homogeneity and extension of the optical pulse duration have been obtained by the peaking of the discharge current with a small stray capacitance between the rail gap and the laser head as well as by the use of Ne rather than He as a buffer gas, resulting in the output energy of 13.8 J in XeCl and 5.0 J in KrF.

60 citations


Journal ArticleDOI
TL;DR: In this article, the effect of buffer gas pressure on specific dissociation rates and the isotopic selectivity was investigated and the intrinsic relation between the fractional conversion per pulse and the fluence by means of deconvolution technique.
Abstract: Multiphoton dissociation of ppm level CTF3 in CHF3 is reported. The effect of buffer gas pressure on the specific dissociation rates and the isotopic selectivity is investigated. Pulse energy dependence of the dissociation rates is converted to the intrinsic relation between the fractional conversion per pulse and the fluence by means of the new deconvolution technique. By addition of 100 Torr argon, the critical fluence of CTF3 was decreased from 136 to 34 J/cm2, while the intrinsic selectivity was increased from 34 to 580. In the absence of buffer gas argon, the fractional conversion per pulse exhibits two different pressure dependences. Unlike in the case below 15 Torr, the system shows strong pressure dependence and loss of the isotopic selectivity above 15 Torr. Possible application to the tritium removal process is also discussed.

53 citations


Journal ArticleDOI
01 Jan 1982
TL;DR: In this paper, the temperature dependence of CH radicals with NO, O2, CO2 and CO2 was studied in the range from 297 to 676K in 100 torr of Ar buffer gas using a two-laser, photolysis/probe technique.
Abstract: The temperature dependence of the reactions of CH radicals with NO, O2, CO2 and CO was studied in the range from 297 to 676K in 100 torr of Ar buffer gas using a two-laser, photolysis/probe technique. The CH radicals were generated by the multiphoton dissociation of CHBr3 at 266 nm and detected by LIF at 429.8 nm. The reactions of CH with No and O2 show very little temperature dependence with k=(1.9±0.3)×10−10 and k=(5.4 ±1.0)×10−11 cm3 molecule−1 s−1, respectively. The rate of reaction of CH with CO2 increases with increasing temperature and can be described in the temperature range studied by k =(5.7±0.9)×10−12exp[(-345±53)/T] cm3 molecule−1s−1. The reaction of CH with CO has a negative temperature coefficient and was also found to be pressure-dependent. The rate constant for the reaction in 100 torr of Ar buffer gas is k=(4.6±1.0) ×10−13 exp [(861±101)/T] cm3 molecule−1 s−1 in the temperature range studied. The rate constant at room temperature increases by a factor of 3 over the range of buffer gas pressure from 50 to 640 torr. These observations are explained in terms of a long-lived complex, the HC2O adduct.

36 citations


Journal ArticleDOI
TL;DR: In this paper, the use of pulsed optogalvanic effect in the detection of inverted population was reported, where an early positive part of the optogalanic signal is shown to be characteristic of a population inversion and is measured using a high temporal resolution from the start of the laser pulse.

31 citations


Journal ArticleDOI
TL;DR: In this article, the atomic polarization of the sodium was determined from the optical rotation of a second dye laser tuned midway between the D lines, and rate-equation calculations reproduce the experimental data and predict very high polarizations with the use of one or more single-frequency dye lasers in thick alkali-vapor targets.
Abstract: Optical pumping by a single-frequency cw ring dye laser of thick sodium-vapor targets (NL>10/sup 13/ atoms/cm/sup 2/) without buffer gas has been investigated for an optically pumped polarized ion source. The atomic polarization of the sodium was determined from the optical rotation of a second dye laser tuned midway between the D lines. Rate-equation calculations reproduce the experimental data and predict very high polarizations (P> or =0.8) with the use of one or more single-frequency dye lasers in thick alkali-vapor targets.

27 citations


Patent
20 Dec 1982
TL;DR: In this article, a lamp primarily containing neon gas is supplied with alternating electrical power at a frequency of not less than 5 kHz and discharge current is determined on the basis of the gas pressure such that no striations occur.
Abstract: A lamp primarily containing neon gas is supplied with alternating electrical power at a frequency of not less than 5 kHz The discharge current is determined on the basis of the gas pressure such that no striations occur If necessary, getter means including a metal element belonging to the second, third, fourth or fifth periodic group are provided near each electrode, oriented so as not to interfere with any electron emissions from the lamp electrodes

23 citations


Journal ArticleDOI
TL;DR: In this article, the beam from a low-divergence KrF laser (λ=248 nm) was used to generate long plasma channels in low pressure gases, with current-carrying channels 60 cm in length with 5 mJ of laser energy.
Abstract: The beam from a low‐divergence KrF laser (λ=248 nm) has been used to generate long plasma channels in low pressure gases. Current‐carrying channels 60 cm in length were produced with 5 mJ of laser energy. Channels exceeding 1 m in length were also initiated. The ionization source producing the plasma is laser‐induced resonant two‐step photoionization of organic molecules which are seeded in a buffer gas.

22 citations


Journal ArticleDOI
TL;DR: In this paper, a CO2 laser-induced multiphoton dissociation (MPD) of C2TF5 and C2HF5 was reported for tritium isotope separation, and single-step separation factors exceeding 500 were achieved with the most efficientP(20) line in 00o-10o0 transition at 944.2 cm−1.
Abstract: Isotope separation of tritium by CO2 laser-induced multiphoton dissociation (MPD) of C2TF5 is reported for the first time. The MPD spectrum obtained for C2TF5 comprised a broad peak at about 940 cm−1 where C2HF5 was nearly transparent. The unimolecular dissociation of C2TF5 was induced with much lower laser fluence than that for CTF3, another working molecule we proposed for laser isotope separation of tritium. The mechanisms and kinetics of the dissociation of C2TF5 and C2HF5 were investigated under various experimental conditions: laser frequency, pulse energy, pulse duration, tritium concentration, sample pressure, buffer gas pressure and irradiation geometry. Single-step separation factors exceeding 500 were achieved with the most efficientP(20) line in 00o–10o0 transition at 944.2 cm−1.

21 citations


Journal ArticleDOI
TL;DR: In this paper, the vibrational relaxation rate constant in the bending manifold for CFCl in Ar was found to be k, = (6.8 f 0.7) X cm3 molecule-l s-l.
Abstract: a third body is needed to stabilize the reaction complex. In this instance the Ar buffer gas would serve as a third body to remove excess energy from the newly formed transient product. Although our present data do not give positive proof that a third body is needed for stabilization, in view of the discrepancy between the present results and those obtained in ref 4, it may be likely. Further, the results of Tiee et al. are in closer agreement with the results of this study, and it is apparent that total pressure differences lead to different rate constants. To resolve this conflict, reaction rate experiments may be carried out utilizing other buffer gases. It is known that different buffer gases lead to different atom and free-radical recombination rate constants. These same effects should occur for termolecular moleculemolecule reactions as well. Conclusion The overall vibrational relaxation rate constant in the bending manifold for CFCl in Ar was found to be k, = (6.8 f 0.7) X cm3 molecule-l s-l. This rate constant may prove to be useful in the correlation of vibrational relaxation studies. However, state-to-state relaxation studies should be performed to determine the exact mechanism for this relatively fast relaxation. Finally, it is hoped that the rates of reaction of CFCl with the nitrogen-oxygen compounds will aid in the formulation of more accurate models for stratospheric chemistry.

17 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examined the process Cl2+Cl−→Cl3− in helium buffer gas and showed that the two-body rate is independent of the pressure of the buffer gas: k = 8.8×10−10 cm3 molecule−1 s−1.
Abstract: Using the flowing afterglow technique, we have examined the process Cl2+Cl−→Cl3− in helium buffer gas. The system was studied over a range of helium pressures and the dependence of the apparent two‐body rate upon the buffer gas concentration gives a three‐body rate constant for the process: k = 0.9×10−29 cm6 molecule−2 s−1. In addition, we looked at the analogous process involving a fluoride ion. There is no evidence for formation of the trihalide Cl2F− under our experimental conditions. A charge exchange process between Cl2 and F− to produce Cl− and neutral ClF does occur, however. This rate is independent of the pressure of the helium buffer gas: k = 8.8×10−10 cm3 molecule−1 s−1.

Patent
26 Apr 1982
TL;DR: In this paper, a method of removing inert gases from a metal halogen electrolyte battery system in which hydrogen is generated along with other inerts such as carbon dioxide, carbon monoxide and oxygen is presented.
Abstract: A method of removing inert gases from a metal halogen electrolyte battery system in which hydrogen is generated along with other inerts such as carbon dioxide, carbon monoxide and oxygen, said method comprising, pressurizing the gas space above the sump to a preset pressure above ambient, and subsequently venting the hydrogen and other inert gases from the gas space through an absorber means which removes trace quantities of chlorine from the gases.

Patent
19 Apr 1982
TL;DR: In this paper, an apparatus for feeding a continuous supply of carbonaceous material into a pressurized reactor for producing a product gas from the material and which contains toxic and flammable gases is described.
Abstract: An apparatus is disclosed for feeding a continuous supply of carbonaceous material into a pressurized reactor for producing a product gas from the material and which contains toxic and flammable gases. The apparatus comprises a first rotary gas lock for receiving the material from ambient atmospheric condition. The first lock is supplied with a flow of nitrogen as a sealing gas to prevent air from entering the lock and the apparatus. The first lock transfers the material to a second rotary gas lock which in turn transfers the material to a screw conveyor for delivery to the interior of the reactor. The second lock is supplied with a flow of a clean product gas as a buffer gas. The clean product gas supplied to the second lock is at a pressure greater than the pressure in the reactor and prevents flow of gases from the reactor to the apparatus. An exhaust is maintained between the first and second locks which draws off nitrogen and clean product gas with the nitrogen and product gas constituting a noncombustible mixture of gases in the exhaust. Means are provided for preventing entrainment of particulate material between the first and second gas locks.

Journal ArticleDOI
TL;DR: In this paper, the lifetimes of 7 levels in the Cu(I) 3 d 9 4 s 4 p configuration were measured using a delayed coincidence technique; copper vapor was excited in an argon buffer gas and cross sections for collisional destruction of copper levels by argon were also obtained.
Abstract: Radiative lifetimes of 7 levels in the Cu(I) 3 d 9 4 s 4 p configuration have been measured using a delayed coincidence technique; copper vapor was excited in an argon buffer gas and cross sections for collisional destruction of copper levels by argon were also obtained. Transition probabilities of the lines originating from these levels have been determined using the measured lifetimes and branching ratios.

Journal ArticleDOI
TL;DR: In this paper, a quantum mechanical thermal average is performed to obtain the temperature dependence of the hyperfine frequency shift (HFS) of hydrogen atoms in the presence of He buffer gas.
Abstract: A quantum mechanical thermal average is performed to obtain the temperature dependence of the hyperfine frequency shift (HFS) of hydrogen atoms in the presence of He buffer gas. The calculations ar...

Journal ArticleDOI
TL;DR: In this paper, a small-size HgBr2 photodissociation laser is operated without buffer gas, and it is shown that in the laser emission as well as in the flourescence spectrum, excited with the wavelength of an ArF laser at 193 nm, approximately the 10 lowest-lying vibrational levels of the B 2 Σ 1 2 + state contribute to the emission.

Journal ArticleDOI
TL;DR: In this article, the backward generation of echoes with three-pulse excitation is discussed in solid and gaseous systems, and the first experiments in a gas were performed on the atomic sodium D 1 line in both the nanosecond and the picosecond region.
Abstract: Backward generation of echoes with three-pulse excitation is discussed in solid and gaseous systems. The backward echo in gases is possible as in solids but with different combinations of incident pulse directions. The first experiments in a gas were performed on the atomic sodium D 1 line in both the nanosecond and the picosecond region. Furthermore, we have observed the first backward echo in a molecular system, that is, in both of the X Σ -A Σ and X Σ -B I I transitions of Na 2 . Decays of the echoes were measured as a function of buffer gas (Ar) pressure, and collisional cross sections due to phase interrupting collisions were evaluated for each of the above cases.

Journal ArticleDOI
TL;DR: In this paper, the electron attachment rate constants of HC1, CCl4, CH3Cl, CH2Cl2, NOCL, and C1F have been measured in electron-beam excited mixtures of the chlorine donor in a majority buffer gas.
Abstract: The electron attachment rate constants of HC1, CCl4, CH3Cl, CH2Cl2, NOCL, and C1F have been measured in electron‐beam excited mixtures of the chlorine donor in a majority buffer gas. The measurements were made by monitoring the electron current decay after termination of the e‐beam pulse, in conditions resembling an e‐beam controlled laser discharge. The possible enhancement of attachment due to vibrational excitation of the chlorine donor under e‐beam pumping was studied by performing measurements with e‐beam currents of 15 and 500 mA/cm2. With the exception of methyl chloride, no enhancement was observed. HC1 attachment was also measured at 5 A/cm2 by a steady‐state technique, and vibrational enhancement was still insignificant. The implications of these results for XeCl laser kinetics are discussed.

Journal ArticleDOI
TL;DR: In this article, an investigation was made of lasing of XeCl* (λ ~308 nm) molecules as a result of electric-discharge excitation of a laser with plasma electrodes.
Abstract: An investigation was made of lasing of XeCl* (λ ~308 nm) molecules as a result of electric-discharge excitation of a laser with plasma electrodes. Mixtures with neon as a buffer gas were subjected to quasicontinuous pumping and emitted laser radiation quasicontinuously. The laser radiation energy was 0.3 J and the efficiency was ~1.4% measured relative to the stored energy.

Journal ArticleDOI
TL;DR: In this article, an investigation into the characteristics of an NH3-N2 laser operating in the passive mode-locked regime was conducted and it was found that adding a buffer gas to the cell made it possible to satisfy the condition ΔνabsΔνg with the minimum possible losses in the absorber.
Abstract: The results are given of an investigation into the characteristics of an NH3–N2 laser operating in the passive mode locked regime. Pulses of ~7 nsec duration were obtained in the range 745–928 cm−1 and the total laser output energy was up to 70% of that without mode locking. The optimal parameters of a gas absorption cell and of the NH3–N2 laser operating regime with a bleachable filter were found. It was found that adding a buffer gas to the cell made it possible to satisfy the condition ΔνabsΔνg with the minimum possible losses in the absorber. A possible procedure was suggested for increasing the power of the NH3–N2 laser by an order of magnitude.

Journal ArticleDOI
TL;DR: In this article, the authors measured the gas temperature on the axis of the discharge gap of a transversely excited copper vapor laser and estimated the efficiency of converting the discharge energy into heat.
Abstract: One of the factors determining the ultimate characteristics of copper vapor lasers is the heating of the active medium by the pulse-periodic discharge providing the excitation. The gas temperature was measured on the axis of the discharge gap of a transversely excited copper vapor laser. Two methods were used: a spectroscopic method (based on the Doppler width of an emission line of the neon buffer gas) and an interferometric method (based on the fringe shift in a Mach–Zehnder interferometer at the instants when the discharge was switched abruptly on and off). Both methods yielded values close 2200 °K. The temperature distribution in the active zone with a rectangular cross section was computed numerically. The results of a theoretical calculation were used to estimate the efficiency of conversion of the discharge energy into heat, which was around 40%.

Journal ArticleDOI
TL;DR: In this paper, the decay of the 6p3 2D03/2 lower active level of the bismuth atom was investigated in the afterglow of a pulsed discharge of a buffer gas.
Abstract: The method of resonant absorption due to the lasing transition was used to investigate the decay of the 6p3 2D03/2 lower active level of the bismuth atom in the afterglow of a pulsed discharge in bismuth vapor containing a buffer gas. It was found that 10−5 sec after the discharge pulse, the decay of the population of the 6p3 2D03/2 level is described by an exponential dependence with the time constant 2×10−5sec.

Journal ArticleDOI
TL;DR: In this article, the steady-state self-focusing and self-defocusing of a circularly-polarized laser beam, occurring in an atomic vapor mixed with a buffer gas at a relatively high pressure, was studied.
Abstract: A theoretical study is made on the steady-state self-focusing and self-defocusing of a circularly-polarized laser beam, occurring in an atomic vapor mixed with a buffer gas at a relatively high pressure. The presence of the buffer gas removes the theoretical difficulties arising from hole-burning, the transit time, and hyperfine pumping. It also localizes the optically-pumped atoms in the vicinity of the laser beam, so that self-focusing occurs even at extremely weak light intensities. A preliminary experiment is also descirbed, the results of which show that optical-pumping self-focusing can be observed at laser intensities down to 30 µW.

Patent
24 Mar 1982
TL;DR: In this article, a process for the measured addition to a carrier gas of small concentrations of a corrosive gas in accordance with the saturation vapour pressure principle, characterised in that the temperature dependency of the dissociation pressure of the gas to be measured, is made use of by means of a chemical adsorber for the gas.
Abstract: of EP00478601. A process for the measured addition to a carrier gas of small concentrations of a corrosive gas in accordance with the saturation vapour pressure principle, characterised in that the temperature dependency of the dissociation pressure of the gas to be measured, is made use of by means of a chemical adsorber for the gas.

Patent
09 Apr 1982
TL;DR: In this paper, the concentration of sulfur trioxides in an FCC unit regenerator is maintained within environmentally accepted limits, while maintaining an adequate amount of gas for fluidizing conditions in the regenerator, by admixing the regenerators oxygen-containing gas with an inert gas.
Abstract: The concentration of sulfur trioxides in an FCC unit regenerator is maintained within environmentally accepted limits, while maintaining an adequate amount of gas for fluidizing conditions in the regenerator, by admixing the regenerator oxygen-containing gas with an inert gas. The quantity of the inert gas is controlled by a control loop measuring the pressure drop in the regenerator, and adjusting the amount of the inert gas to maintain the pressure drop within the predetermined limits.

Patent
23 Feb 1982
TL;DR: In this article, the ratio of the amount of flue gas to the number of combustible components in the fuel gas is used to control the Claus process in the combustion of gaseous fuels containing inert gas.
Abstract: In the combustion of gaseous fuels containing inert gas, the pure oxygen feed is increased and the air feed is reduced to compensate for the variations in the proportions of inert gas in the fuel gas during operation, the pure oxygen feed being reduced if the amount of inert gas in the fuel gas rises and the air feed being increased if the amount of inert gas in the fuel gas decreases. In particular, the amount of ballast gas, that is to say the sum of the amount of inert gas in the fuel gas and the amount of nitrogen in the combustion air, is kept constant. The control can be carried out by means of the ratio of the amount of flue gas to the amount of combustible components in the fuel gas. The method can be used, in particular, in the Claus process.

Proceedings ArticleDOI
02 Jun 1982
TL;DR: In this paper, the light shift and buffer gas shift in passive rubidium frequency standards were measured for two configurations: the separated filter and the integrated filter approaches, and a phenomenological analysis, which describes well the results obtained, was presented.
Abstract: : Results of calculation and measurements on the light shift and buffer gas shift in passive rubidium frequency standards are reported. The light shift was measured for two configurations: the separated filter and the integrated filter approaches. A phenomenological analysis, which describes well the results obtained, is presented. Measurements of the frequency shifts created by various buffer gases-pure or mixture- are reported. A nonlinear dependence of frequency versus temperature is observed. The results are compared to already published data and a simple analysis using an equation quadratic in temperature is used to explain those results. (Author)

Journal ArticleDOI
TL;DR: In this paper, the results of experimental investigations on generation in Ar(Ne): Xe: CCl 4 (HCl) mixtures at excitation by an electron beam are given.

Journal ArticleDOI
TL;DR: In this article, an experimental investigation was made of the energy characteristics of an XeCI laser pumped by a high-current proton beam which deposited energies up to 1 J/cm3 in the gas mixture.
Abstract: An experimental investigation was made of the energy characteristics of an XeCI laser pumped by a high-current proton beam which deposited energies up to 1 J/cm3 in the gas mixture. The replacement of Ar (used as a buffer gas) with He increased the laser output energy and efficiency. The laser radiation energy obtained for a He:Xe:CCl4 = 750:50:1 mixture was 1.5 J when the specific input energy was 15 J/liter and the lasing efficiency was 6%. "Overheating" of the mixture was observed at high input energies and this reduced the laser radiation energy and eventually quenched the lasing action.

Journal ArticleDOI
TL;DR: In this article, pressure broadening coefficients have been measured for 12C18O2 at 2.7 μm broadened by buffer gas species CO2, H2, He, O2, N2, Ar, and Xe.
Abstract: Pressure broadening coefficients have been measured for 12C18O2 at 2.7 μm broadened by buffer gas species CO2, H2, He, O2, N2, Ar, and Xe. The results, expressed as self-broadening efficiencies, are compared with data for other transitions from 1.6 to 10.4 μm.