K. Rózsa

Near infrared CW laser oscillation in Cu II

Abstract CW laser oscillation was observed at the 7808 A transition of Cu II in HeNeCu, HeArCu, and HeKrCu hollow cathode discharges. The role of the noble gas mixture in obtaining laser action is discussed.

EFFECT OF DIFFERENT ELEMENTARY PROCESSES ON THE BREAKDOWN IN LOW PRESSURE HELIUM GAS

We investigated the breakdown in low-pressure helium gas both experimentally and by computer simulations. At low breakdown voltages (VBR 1000 V) the experimental and simulation results show a good agreement (differences are within 20%), while at higher voltages the simulations and experiments agree qualitatively. Our simulations indicate that several processes contribute to the particular shape of the Paschen curve in helium at low pressures. These processes are: (1) the dependence of the (ion-induced) secondary electron emission yield on the ion energy, (2) the appearance of ion impact ionization of the gas at high electric fields and (3) the secondary electron emission from the cathode due to fast neutral atoms.

Noble gas mixture CW hollow cathode laser with internal anode system

Abstract 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 A Kr ion and the 4765 A Ar ion transitions. CW laser oscillation was observed for the first time at the 5314 A and 4863 A transitions of Xe II.

CW Cu II laser in a hollow anode-cathode discharge

Abstract CW laser operation on near infrared transitions of Cu II was investigated in a high voltage hollow cathode discharge tube of 19 cm active length. The high voltage was obtained by a special anode system placed inside the cathode. Threshold current for the strongest 7808 A laser line was 0.4 A. At a discharge current of 2.4 A a multiline output power of 30 mW was obtained on six transitions between 7404 and 7896 A.

Hollow Cathode Discharges for Gas Lasers

A review of hollow cathode discharges for gas (metal vapour) lasers is given. Particular attention is paid to the arc free discharge region and to the possibility of increasing the intensity of the ionic spectrum of the discharges

Parametric study of a high-voltage hollow-cathode infrared copper-ion laser

A new, segmented-electrode, high-voltage, hollow-cathode, Cu II laser, operating on the 780.8 and 782.5 nm transitions, is studied. Parametric measurements are presented for the discharge voltage, the spatially averaged copper-atom concentration and, for the two transitions, the small-signal gain coefficient, the laser threshold current and the laser output power. The dependence of the laser output power on the active length, the buffer-gas pressure and the transmission of the output coupler is modelled using equations for a low-loss, homogeneously broadened, standing-wave laser. For the 780.8 nm line, the lowest threshold current is 0.19 A for a 5 cm active length and a 0.1% transmission output coupler, and the maximum output power is 58 mW for a 3 A discharge current, a 7.5 cm active length and a 2% transmission output coupler. This performance exceeds that of conventional hollow-cathode lasers on the same transition, the improvement being attributed to the increased operating voltage, which gives a more efficient pumping discharge by simultaneously raising the ground-state copper-atom concentration (through the increased sputtering yield of ions bombarding the cathode) and increasing the efficiency of ionization.

CW aluminum ion laser in a high voltage hollow cathode discharge

Abstract Laser oscillation on transitions of Al II was investigated in a large diameter hollow cathode discharge where Al vapour was produced by cathode sputtering. The special internal anode system used considerably increased the tube voltage and resulted low threshold currents.

Deposition rates in direct current diode sputtering

A physical model for anode deposition rates in parallel‐plate, dc‐diode sputtering is presented and tested. The deposition rate has been measured as a function of the discharge voltage, the anode–cathode gap and the pressure, using silicon or molybdenum cathodes with argon. Deposition rates as high as 23 A/s were obtained using 3 kV, and it is shown that deposition efficiency is similar to that obtained with magnetrons. The deposition rate varies inversely with anode–cathode gap at constant pressure and voltage and almost linearly with power density for discharge voltages above a threshold which depends on the cathode material. These observations are explained by the model, which can be used to estimate the deposition rates for any cathode material and gas for which the ion sputtering yields are known. Potential advantages and complications of dc diode sputtering for thin film deposition are discussed, and optimum conditions for high, uniform deposition rates are described.

Investigation on a continuous wave 4416 Å cadmium ion laser

Measurements have been carried out on the output power, gain and oscillation bandwidth of a continuous wave 4416 A Cd ion laser. Optimum parameters for laser operation are obtained, the results of measurements indicate the possibility of two processes in the excitation mechanism.

He-Kr ion laser in a d.c. hollow cathode discharge

Abstract Laser oscillation at the 469.4 nm and 431.8 nm transitions of Kr II was obtained in a d.c. hollow cathode He-Kr discharge. Optimum He and Kr partial pressures were found to depend on discharge current; a gain of 6.7%/ m and an output power of 5 mW was measured at 469.4 nm.