Spectroscopic investigation of laser-initiated low-pressure plasmas in atmospheric gases.
Laser-initiated breakdown of N2, O2, and Ar has been investigated at sub-atmospheric pressures using a pulsed (10-nsec) Nd:yttrium aluminum garnet (Nd:YAG) laser at 1.06 μm. Breakdown thresholds have been determined from 3 to 760 Torr, and spectral analysis of the plasma emission has been carried out at 10 and 125 Torr over the 300–600-nm range. Sharp spectral features arising from highly excited singly and multiply charged ions are reported as well as an underlying continuum at intermediate pressure. Time-resolved measurements indicate a complex kinetic dynamic optical behavior.
Experimental investigation of electrical breakdown in nitrogen and oxygen induced by focused laser radiation at 1.064 μ
The characteristics of laser‐induced breakdown in N2 and O2 at a wavelength of 1.064 μ were investigated using 10‐nsec pulses for pressures ranging from 1 to 50 atm. The pressure dependence of the experimentally determined threshold field intensities for these two gases is essentially the same except at the lowest pressures where the O2 values are slightly lower than those for N2. Comparison of this data with existing microwave data can be accomplished most directly by means of a ’’universal plot’’ of the type used effectively in the latter case. The general trends of the microwave and optical data are essentially the same; however, actual numerical values for the optical data tend to be lower than the corresponding microwave values by a constant factor of roughly 0.5. The fact that the two sets of data correspond so closely in spite of the large difference in frequencies has to be regarded as providing substantial evidence supporting the validity at optical frequencies of the cascade theory of breakdown ...
Industrial Relations in 1988
Undoubtedly, the election of the Hawke Labor Government in 1983 marked a turning point in Australian industrial relations. To a large extent industrial turbulence receded, helped along by global econ omic instability and the influence ofthe Prices and Incomes Accord between the Australian Labor Party and the Australian Council of Trade Union (ACTU). Arguably, the apparent success of the Accord owed something to a widespread concern within unions that the election of a Liberal-National Party government at the federal level would have resulted in a major pro gram of economic regulation, especially in relation to the institutions ofthe labour market. During 1988, despite an increasingly buoyant economy, the continuing influence of these economic and political conditions ensured that the level of industrial disputation remained subdued by historical stan dards, though those opposed to the nascent corporate state or centralised wage fixing may have been heartened by signs that wage restraint was fraying at the...