A measurement has been made of the electron impact ionization cross section of F2 and Cl2 over the energy range 15–100 V. Both species exhibit a maximum cross section at electron energies near 100 eV, the maximum values being approximately 1.5× 10−16 and 7.0× 10−16 cm2 for F2 and Cl2, respectively. The measurement in Cl2 fits an observed correlation between the maximum cross section and the square root of the polarizability. This correlation seems to apply to a wide variety of atomic and molecular species. Based on this correlation we estimate the polarizability of F2 to be approximately 8× 10−25 cm3

Vacuum ultraviolet absorption cross sections for the compounds Cl2, Br2, I2, HCl, HBr, HI, CCl4, CCl3Br, CF3Br, CF3I, HgCl2, HgBr2, and HgI2 have been measured between 170 and 230 nm. Studies of the Xe*2 discharge lamp used are reported. The absorption bands of various mercuric halides are identified.

A new approach (ThinZag®) for scaling Nd:YAG solid-state slab lasers to high power levels is described. Using an innovative optical configuration, thin slabs of solid-state gain material are immersed in a flowing cooling fluid, resulting in improved thermal management. Measurements at the ~1 kW level were conducted to compare Nd:YAG ceramic with Nd:YAG crystalline slabs. The ceramic slabs demonstrated comparable laser output power relative to the more standard crystalline slabs and demonstrated better optical properties, which result in improved medium uniformity. Performance results from our nominally 5 kW and 15 kW modules are also presented. The 15 kW modules represent basic building blocks for the Joint High Power Solid State 100 kW Laser (J-HPSSL) currently being designed and developed by Textron Defense Systems. Recent measurements of three nominally 15 kW modules operating as a single aperture power oscillator where outputs to 30 kW with beam quality of 3.3 XDL were measured are also included. The reported powers were for operation below maximum pump rate of the device.

The absorption spectrum of the negative ion of fluorine has been observed in shock-heated vapors of CsF. The photodetachment cross section of the fluorine ion has been measured in the wavelength region between 2100 and 3600 A.. Results are found to be in reasonable agreement with the calculated values of Robinson and Geltman.

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