O 2 (a  1 Δ g ) was generated in a flowing discharge of a radio-frequency (rf) hollow electrode. The radio frequency was 99.9 MHz and the rf power was 200 W. The discharge was done in the gas mixture O2:N2:NO=200:20:10 sccm and then it was chilled reactively by the mixture Ar:NO2=200:10 sccm. The O2(a 1Δg) relative yield of 32% was achieved at the pressure of 0.43 Torr. Usage of the mixtures O2:NO=200:100 sccm and Ar:NO2=100:100 sccm resulted in the O2(a 1Δg) yield of 25% at the pressure of 0.6–0.9 Torr. The effluent was mixed with molecular iodine in a far afterglow region and it was tested in an oxygen–iodine laser. The iodine flow rate was 0.3 mmol/min. A strong enhancement of atomic iodine spontaneous emission at the wavelength of 1315 nm was observed in the optical resonator.

A scaling up of kW-c1ass chemical oxygen-iodine laser (COIL) is achieved. The key issues for the system design of COIL for industrial application is discussed. The scaled up COIL system of l-kW output power is now under trial operations. In these operations, a maximum output power of 1100 W, and a continuous operation time of more than 2 h with a power of over SOO W is recorded.

This study was performed to obtain fundamental knowledge concerning the development of laser pressure welding technology for the joining of dissimilar metals. Laser pressure welding of Al alloy A6061 and low C steel SPCC sheets was carried out to investigate the effects of the roller pressure, laser beam scanning speed and irradiation position on the tensile shear and peel strength of welded joints. The interfaces of the joints were observed and analysed by SEM and EDX, and the formation phases on the peeled surfaces were identified with XRD. It was revealed that prevention and suppression of oxidation during welding was extremely important to the production of a sound joint with good mechanical properties. The highest tensile strength and the highest peel strength of joints were obtained at a laser power of 1 . 8 kW, laser scanning speed of 30 Hz, laser irradiation position at the centreline, roller pressure of more than 245 MPa and welding speed of 0 . 5 m min -1 in an Ar atmosphere. The fracture occurred not in the welded zone but in the A6061 base alloy specimen.

An RF plasma jet generator of singlet delta oxygen has been developed for use in an oxygen-iodine laser. The plasma jet was produced in an Al cylindrical nozzle, having the inner diameter of 3 mm and the length of 8 mm. The discharge was done in the gas mixture 02:N2:NO=200:20:lO sccm and then it was chilled reactively by the mixture Ar:N02200:1O sccm, which was injected into the plasma jet at the nozzle exit. The RF frequency was 99.9 MHz and the RF power was 200 W. The O2(a'A) relative yield of 32 % was achieved at the pressure of 0.43 Ton. The current device DSOG-3 was tested in a discharge oxygen-iodine laser (DOlL). The reaction scheme of DOlL is the same as in COIL, except of the generator of singlet delta oxygen. The pressure inside the laser was 0.6-0.9 Torr and the mixtures 02:N0200: 100 sccm and Ar:N02100: 100 sccm were used. The iodine flow rate was 0.3 mmol/min. Both types axial and transverse subsonic flow lasers were examined. The latter had better performance. The CW output power was 3 nW at the laser wavelength of 13 15 urn, when the yield ofO2(a'A) was 25%. The RF DOlL has been demonstrated experimentally.

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