Noble gas mixture CW hollow cathode laser with internal anode system

A hollow cathode discharge tube with internal anodes was found to operate at significantly higher discharge voltages than a conventional HCD. A laser tube having internal anodes was constructed and laser operation was investigated in He-Kr, He-Ar and He-Ne-Xe gas mixtures. Due to the increased voltage low threshold currents and increased output power were obtained at the 4694 Å Kr ion and the 4765 Å Ar ion transitions. CW laser oscillation was observed for the first time at the 5314 Å and 4863 Å transitions of Xe II.     

Output characteristics of a hollow cathode He-Cd laser

Optimum discharge conditions, gain and oscillation linewidth were determined for the blue (4416 Å), green (5378, 5337 Å) and the red (6360, 6355 Å) transitions of a hollow cathode He-Cd laser. A total peak output power of 75 mW has been obtained at 5378 and 5337 Å. Mode investigations showed that the green and red transitions operate in a single axial mode, while the blue one does not.     

CW laser oscillation at 8096 Å in Cu II in a hollow cathode discharge

CW laser oscillation at 8096 Å in a He-Cu hollow cathode discharge is reported. Lower thresholds have also been observed for nine previously reported transitions.     

High-pressure gas lasers on Ar I,Xe I,and Kr I transitions

Lasing has been obtained in a high pressure (up to 17 atm) gas on Ar I, Xe I, and Kr I transitions. The gas was excited by a transverse discharge with volume preionization by a discharge through a dielectric. New laser lines belonging to Ar I (9123, 9658, 10470, and 11488 Å), Xe I (8232 Å), and Kr I (8929 Å) have been found. The dependences of the spectral and energetic characteristics of the He-Ar laser on the conditions of gas pressure and discharge have been investigated in detail. At high pressures, wide (about 50 HGz) laser lines have been found as well as high power (>10⁵ W) laser lines. Time characteristics of the radiation have been investigated and optimal conditions for the generation power have been defined.     

CW laser oscillation on transitions of Tl+ in a hollow-cathode Ne-Tl-halide discharge

CW laser oscillation on Tl⁺ transitions (594.9 nm and 695.1 nm) at low operating temperatures is obtained. As a source of Tl atoms the volatile salt TlCl is used. The compound is evaporated due to selfheating by the discharge current. Maximum laser intensity is obtained at neon pressure of 10–13 Torr and cathode temperature ≈ 320°C.     

Enhancement of laser power at 7588 Å in HeZn hollow cathode laser by the addition of xenon

The effects of inert gas additives on the laser output power in the HeZn hollow cathode laser are investigated. The increase of nearly 50% in the laser power at 7588 Å has been observed when a small amount of xenon was mixed into the HeZn hollow cathode discharge tube. The mechanisms of the enhancement of the 7588 Å laser output by the addition of xenon are discussed.     

Experimental investigation of the hyperfine spectra of Pr I – lines: discovery of new fine structure levels with low angular momentum

We present 39 odd and 15 even parity newly discovered fine structure levels of Pr I with low angular momentum: J = 1/2, 3/2 and 5/2. Spectral lines in the range 4200 Å to 7500 Å were experimentally investigated using laser induced fluorescence spectroscopy in a hollow cathode discharge lamp. The levels were discovered by analysis of the recorded hyperfine patterns of the investigated transitions. With the help of these levels, 119 spectral lines were classified directly by laser excitation and 127 lines were classified as fluorescence lines.     

Power limitations of the cw He-Hg laser

The variation of output power with discharge current in the hollow-cathode cw He-Hg laser has been investigated. In strong contrast to the comparable data for the positive-column discharge, the 6150 Å transition shows no turnover in output power with increasing current. Laser powers approaching 100 mW (cw) have been achieved at 6150 Å using a 3mm-bore, 50cm-long tube. Investigation of the excitation mechanisms for the 6150 and 7945 Å transitions confirms both are excited by thermal energy charge transfer reactions.     

Cold-hollow-cathode arc discharge in crossed electric and magnetic fields

A crossed-field cold-hollow-cathode arc is stable at low working gas pressures of 10⁻²–10⁻¹ Pa, magnetic-field-and gas-dependent arcing voltages of 20–50 V, and discharge currents of 20–200 A. This is because electrons come from a cathode spot produced on the inner cathode surface by a discharge over the dielectric surface. The magnetic field influences the arcing voltage and discharge current most significantly. When the plasma conductivity in the cathode region decreases in the electric field direction, the magnetic field increases, causing the discharge current to decline and the discharge voltage to rise. The discharge is quenched when a critical magnetic field depending on the type of gas is reached. Because of the absence of heated elements, the hollow cathode remains efficient for long when an arc is initiated in both inert and chemically active gases.     

CW laser oscillation in a hollow cathode HeAr discharge

CW laser oscillation was observed at the 4765 Å transition of Ar II in a hollow cathode HeAr discharge.     

CW laser oscillation in a hollow cathode He-Kr discharge

CW laser oscillation on the 4694 Å transition of Kr II has been observed in a hollow cathode He-Kr discharge.     

Optimization of the UV CuII laser

The cw output power of the uv CuII laser has been optimized with respect to the hollow cathode geometry, the discharge current, the fill gas pressure and the resonator mirror parameters. A maximum laser output power of 900 mW for multiline operation at 248.6, 259.1, 260.0, and 270.3 nm was achieved with 100 A discharge current, 260 V voltage and 16 mbar fillgas pressure, when a hollow cathode of 1.2 m length and 2×6 mm² cross section was employed. The single-pass pain gl has been estimated to 7%. A hollow cathode cross section of 1.5×4.5 mm² is suggested as an optimum geometry. In addition, some investigations on the mechanism of the laser power decay in Ne–Cu-discharges are presented.     

CW laser oscillation observed on visible and near-infrared PbII-transitions in a hollow cathode discharge tube

For the first time CW laser oscillation of the 537.2 nm and 1.32 μm transitions of PbII has been obtained in a hollow cathode discharge tube in which the lead vapor density was created by discharge sputtering of the lead cathode. In addition two new PbII laser transitions at 666.0 nm and at 839.6 nm were observed, operating CW and quasi-CW, respectively.     

Hollow-cathode transverse discharge He−Ne and He−Cd+ lasers

An all-metal hollow-cathode laser tube consisting of a perforated cylindrical cathode surrounded by a coaxial cylindrical anode has been operated as a He?Ne laser at 0.6328, 1.15 and 3.39 μm, and as a He?Cd laser at red, green and blue visible wavelengths, using both de and pulsed-plus-dc excitation. Laser oscillation in He?Zn, Ne?Cd, Xe?Cd and Ar?Cd mixtures has also been obtained. The hollow-cathode discharge consists primarily of an intense cathode glow inside the cathode cylinder, giving a quiet, stable, low-voltage, positive-resistance discharge. Results for the He?Ne and He?Cd laser output versus partial and total pressures and discharge currents are presented. The unoptimized laser performance for the He?Ne case approaches but does not yet equal the conventional positive-column case, while the He?Cd performance for the charge-transfer-pumped green 5378Å line appears particularly promising.     

Pulsed 469.4 nm hollow cathode He-Kr laser

Design principles, construction and operation characteristics of a pulsed 469.4 nm He-Kr laser are described. The laser was operated in a 20 cm active length transverse hollow cathode discharge and was excited by 50 Hz repetition rate 0.1–1 ms duration square wave current pulses. Cataphoresis of Kr ions was found to play an important role in forming the laser pulse shape. By increasing the voltage a considerable increase of peak laser power occurred, the maximum power obtained was 80 mW. The sealed-off laser was operated using 400 s, 4 A current pulses, pulsed laser power being 20 mW, average power 0.4 mW, respectively. The lifetime of the laser was 440 h, tube failure being due to gas cleanup caused by cathode sputtering.     

Systematic trends in optogalvanic signals of some transitions in a uranium hollow cathode discharge

A study of optogalvanic (OG) signals in a uranium hollow cathode discharge using a tunable pulsed dye laser with intensities above saturation revealed certain systematic trends. The peaks of OG signals, for a given hollow cathode current, due to all transitions involving the ground state are within a certain range of values. The same is true of the OG signals due to transitions involving the 620 cm^-1 and 3800 cm^-1 lower metastable levels. For all transitions involving the same lower state, the peaks of OG signal vary linearly with the discharge current. The slopes of such straight lines are different for transitions involving different lower levels of uranium. Effects of radiation trapping are seen in the OG signals due to transitions involving the ground state of uranium at currents above 60 mA. Details of our observations are presented and discussed.     

Laser action ofnd 8(n + 1)s 2 −nd 9(n + 1)p transitions in HgIII,Cull and AgII

A mechanism of the laser action of 5d ⁸ 6s ² –5d ⁹ 6p HgIII transitions is proposed. The explanation is based on atomic constants of the transitions and the predominant role of direct electron excitation of the upper laser level. The kinetic models of electron beam and hollow cathode discharge sources are calculated. The theoretical estimations are compared with experimental data and possible laser transitions are also proposed. The role of electron impact excitation in the formation of inverse population for two-electron transitions in CuII and AgII obtained in hollow cathode discharges is discussed.     

Plasma cathode TEA Ar laser development

The plasma cathode design concept is applied to an Ar laser for the first time. The sliding discharge is used as a plasma cathode for the main laser discharge. The laser operates at atmospheric pressure with a gas mixture of Ar/He/SF₆. Results concerning the dependence of the laser performance on the gas mixture flow rates and charging voltage are presented. The temporal behavior of the laser output is also presented. Output energies as high as 2 mJ, efficiency and specific energy extraction values up to 1.3×10⁻²% and 0.02 J/l respectively, at atmospheric pressure, are obtained. The spectroscopic examination of the output shows that lasing at 1.79 and 1.27 μm is obtained with approximately equal line intensities.     

Simultaneous cw laser oscillation on transitions of Cd+ and I+ in a hollow-cathode He-CdI2 discharge

Continuous-wave laser oscillation has been obtained on four transitions of Cd⁺ and eleven transitions of I⁺ using a hollow-cathode He-CdI₂ discharge as active medium. Laser output characteristics are similar for both Cd⁺ and I⁺ transitions, and simultaneous cw oscillation has been achieved at wavelengths ranging from blue (4416 Å Cd⁺) through green $\text{(}\text{5337}\text{5378}$ Å Cd⁺, 5407 Å I⁺), yellow $\text{(}\text{5678}\text{5761}$ Å I⁺) and orange (6127 Å I⁺) to red (6585 Å I⁺).     

小型空心阴极等离子体电子枪实验

基于空心阴极效应和低压辉光放电原理,设计了一种小型空心阴极等离子体电子枪并进行了实验研究,在低气压下获得了稳定的空心阴极辉光放电,测量电子枪放电结果表明：在空心阴极中加入灯丝热子可明显降低放电气压;电子束电流的大小随放电电压增大而增大,受气体气压影响较小;在气压2 Pa,放电电压10 kV,脉宽4 μs脉冲下放电,可得到脉宽为2 μs,电流为600 mA的电子束。