Stability of the conditions for excitation of atomic spectra in plasma produced on exposure of copper alloys to laser radiation

We show that the temperature of plasma produced by exposure of copper-zinc alloy specimens to laser radiation changes little (within the limits of random errors) with a change in the conditions of the laser effect and chemical composition of the specimens. With use of electric discharges (a low-voltage spark), systematic changes in the temperature of the plasma are observed when the chemical composition of copper-zinc alloys changes. Institute of Molecular and Atomic Physics of the National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 319–321, May–June, 1998.     

Coherent excitation of multilevel systems by laser radiation

Different problems of coherent quasi-resonant excitation of multilevel systems in monochromatic radiation fields are discussed. Analytically solvable examples are presented, and, on this basis, some principal effects of cohrent multilevel dynamics are treated.     

钾蒸汽中双光子激发产生2~3∏_g—α~3∑_u~+扩散带受激辐射

本文报道了在K_2-K中通过双光子共振激发原子或双光子激发分子产生2~3∏_(?)—a~3∑_u~+扩散带辐射的实验结果,并对激发机制以及扩散带辐射随激发能量和温度的变化进行了讨论.     

EUV radiation characteristics of a CO2 laser produced Xe plasma

A CO₂ laser-driven Xe liquid jet plasma has been studied with respect to its usability as a EUV lithography light source. A short-pulse TEA-CO₂ master oscillator power amplifier system (MOPA) and a pre-pulse Nd:YAG laser were used for the plasma generation. The dependence of EUV plasma parameters, e.g., conversion efficiency, plasma image, in-band and out-of-band spectra, on the delay time between the pre-pulse and the main pulse laser was investigated. A maximum conversion efficiency of 0.6% was obtained at a delay time of about 200 ns. In addition, characteristics of fast ions were measured by the time-of-flight method. The peak energy of the fast ion energy distribution decreased significantly at delay times longer than 200 ns. This result is very promising with respect to a collector mirror lifetime extension by magnetic field mitigation. PACS 52.50.Jm     

Diagnostics of the temperature of a plasma created by a CO2 laser,from the UV radiation spectrum

Delivered at the Fifth All-Union Conference on Diagnostics of a High-Temperature Plasma (18–22 June, 1990, Minsk).     

Ion wave excitation by radiation pressure in a plasma waveguide

After turn-off of high-power pulsed microwaves, a large-amplitude ion wave is generated which has half of the wavelength of the guided wave. The electromagnetic radiation pressure is responsible for the excitation of the ion acoustic wave.     

Ion spectrum under excitation of a cluster beam by a laser pulse

A model describing the decay dynamics of large charged clusters formed during the interaction of a short laser pulse with a cluster beam is constructed. It is shown that the dynamics of the evolution of the cluster plasma and the energy spectrum of ions are affected by the presence of the decay products from neighboring clusters and the electron background due to ionization. The parameters of the plasma being formed are determined as functions of the cluster beam and laser pulse parameters.     

Interaction of intense CO2 laser radiation with a dense laser produced carbon plasma

A high density laser produced carbon plasma is heated with the beam from a pulsed CO₂ laser. The evolution of the electron density profiles is studied by interferometry.     

Electron-ion recombination in a helium plasma produced by laser

Experimental investigation of the recombination coefficients in a helium plasma produced by laser is reported. The relative contribution of electronic collision processes and of atomic collision processes on the values of the recombination coefficients are pointed out according to the value of the neutral pressure of helium.     

On the theory of Lamb wave excitation in metals by pulsed laser radiation

The problem of pulsed photoacoustic transformation is solved for ferromagnetic metal plates. The effect of the temperature dependence of the thermal coefficient of linear expansion on the spectrum of Lamb waves excited by pulsed laser is revealed.     

Laser produced plasma heated by two simultaneous laser pulses

A single laser pulse plasma heating and that of two simultaneous pulses with different frequencies and the same front pulse shaping are compared in a one-dimensional model.     

Ar plasma waveguide produced by a low-intensity femtosecond laser

Using the interaction of a low-intensity femtosecond laser pulse (30 fs, 6 × 10¹⁵ Wcm^? 2) with argon cluster jet produced from a slit nozzle, we experimentally probe the formation of a uniform plasma waveguide by the interferogram analysis. The results about evolution of plasma channel demonstrate that it is feasible to produce the plasma waveguide for an fs laser pulse of low-intensity. It takes tens of nanoseconds to form a plasma waveguide. The simulation by one-dimensional Gaussian plasma hydrodynamic expansion model indicates that the temperature of plasma channel is not high under this condition. Thus it takes tens of nanoseconds to form a plasma waveguide.