Showing papers on "Buffer gas published in 1967"

Gain characteristics of CO 2 laser amplifiers at 10.6 microns

Abstract: Single-pass gain at 10.6 microns has been studied parametrically in nonflowing CO 2 or buffered CO 2 amplifying media. The gain profile across the amplifier diameter and integrated gain both were determined. Parameters varied included buffer gas type, mixture ratio, gas pressure, amplifier bore, discharge current, and wall temperature. Tube bores of 12, 22, and 34 mm and buffer gases of H 2 , He, Ne, A, and N 2 were studied. Optimum gain is relatively independent of current density, but decreases with increasing wall temperature. The pressure-diameter relationship P_{CO_{2}} \cdot D \sim 4 torr-cm was found to hold for CO 2 , CO 2 :He, and CO 2 :N 2 amplifying media at optimum gain. The gain depends strongly on the CO 2 partial pressure and is relatively insensitive to the buffer gas pressure except for the case of H 2 . The maximum gain decreased slowly with increasing amplifier diameter. The highest gain, 1.7 dB/meter, was achieved with a helium buffer gas in amplifiers with a diameter of 22 mm or less. No gain saturation was detected for a 30-dB range of input signal power, from a milliwatt to a few watts. Spectrograms showed that the principal spontaneous emission from CO 2 :He amplifiers in the 2000-7000-A range consisted of CO bands; no CO 2 bands or He line spectra were observed.

Wirkungsquerschnitte depolarisierender Stöße von angeregten Natriumatomen mit Edelgasatomen durch optisches Pumpen mitD2-Licht

Abstract: Optical pumping of sodium vapor withD2-light causes a rise of optical transparency if complete collision-induced mixing takes place among the sublevels of the excited2P-states. It causes a drop of optical transparency if there would be no mixing in the excited states. It causes no change of optical transparency if excited-state mixing is as strong as the condition 2T=3τ predicts,T being the mean collision time, τ the mean life time of the excited states. The latter case can be realized by certain buffer gas pressures. These pressures have been measured for the gases helium, neon, and argon. From these pressures excited state-mixing cross sections have been deduced by means of the quoted condition. Finally the so far used “uniform” mixing model has been critically revised. A more realistic model is proposed which ascribes excited-state-mixing to scattering phase shifts between the molecularσ- andπ-states into which the atomic2P-state splits during the collision. Nevertheless, the condition 2T=3τ is not seriously altered even in this refined model.

Chemical Reversibility and Solar Excitation Rates of the Nitrosyl Chloride Photodissociative Laser

Abstract: Chemical reversibility of the nitrosyl chloride photodissociative laser is achieved by addition of a large excess of chlorine which also serves as an efficient buffer gas, and thereby eliminates the need for helium. Consideration is given to the prospect of utilizing this system as a means of converting solar radiation to monochromatic coherent emission.

A new method for the study of the diffusion of optically oriented atoms in a buffer gas

Abstract: We describe a new method for studying the diffusion and relaxation of an optically oriented vapour inside a buffer gas. By measuring the rotatory power of the criented vapor for light whose frequency is near that of an absorption line, the vapour’s polarization can be recorded continuosly during the relaxation or the diffusion process. Moreover, since the spectral distribution of this light is outside that of the absorption line, the vapour’s polarization is practically unperturbed by the detection process. The vapour is contained in a cylindrical cell. By means of a pulse of circularly polarized light we pump the vapour into a small cylindrical region of the cell. A second beam of linearly polarized light parallel to the pumping one (the analysing beam) travels inside the cell at a distance Δx from the oriented region. To every pulse of the orienting light a signal is obtained from a polarimeter, showing that the plane of polarization of the analysing beam rotates owing to the diffusion of the atoms, oriented by the pumping pulse, into the region of the cell scanned by the analysing beam. This signal is delayed by a timeT(x) from the pumping pulse. By measuringT(x) as a function of Δx, it is possible to obtain the diffusion coefficientD and the cross-section for disorienting collisions against the buffer gasσ. The experiment has been carried out orienting sodium vapour in He as a buffer gas.

Optisches Pumpen an Cs 133 unter Anwendung einer neuen Nachweismethode

Abstract: Optical pumping on Cs133 atoms was performed by means of a new transmission technique. The cesium vapor was pumped towards equilibrium by an intensive circulary polarizedD1 orD2 light beam. A weakD1 detecting beam was polarized alternately σ+, σ− and allowed one to measure continuously amount and sign of the absorption difference between σ+ and σ− light. The measured signals are proportional to the electron spin polarization. The new technique was used to investigate the influence of Cs buffer gas collisions on the pumping cycle and to measure the influence of radio frequency induced Zeeman transitions on the ground state polarization. In addition the variation of magnetic field and of pumping light intensity and polarization was studied. Some measurements demonstrate the high sensitivity of the applied method. The obtained qualitative results are discussed and further experiments are proposed.

Modulation of the 3.39‐μ Ne Line by Electro‐Optic Gases

Abstract: The Stark effect in several vibrational‐rotational transitions in various gases which have the first vibrational excitation (the C–H stretching vibration) close to the 3.39‐μ transition in neon have been studied in detail. Tuning of the source line from a He–Ne laser over a range of about 0.1 cm−1 was obtained by use of a solenoid. Observations were made of absolute and percentage modulation at various pressures of the gases and included the use of a buffer gas. Maximum modulation of 15% has been achieved. The possibilities for increasing this value and for attaining induced birefringence are also discussed.

The rotatory power of optically pumped atoms

Abstract: Recently the rotatory power of optically pumped vapours has been shown to be very useful as a monitoring technique in opticalpumping experiments. In this work the specific rotatory powerϑ is calculated for any atom. The dependence of the refractive index and ofϑ on the frequency of the light is calculated for unperturbed lines. We also study the connection betweenϑ and the vapour polarizationP for any alkali metal with nuclear spinT in the case of spin temperature. For optical pumping with a buffer gas we find thatϑ is proportional toP within experimental errors in all practical cases. The experimental results are in agreement with this assumption.

Sorption of inert gas ions by titanium.

Abstract: Apparatus and experimental technique for studies of inert gas ion sorption by vapour-deposited titanium films, by compact-grained and coarse-grained titanium and by a titanium monocrystal were observed. The curves of thermal desorption and the quantity of the gas sorbed are given as a function of the nature of the target and the gas under study. Analysis of the experimental results is reported.