Generation of High-Power Light Pulses at Wavelengths 1.06 and 0.53 μ and Their Application in Plasma Heating. II. Neodymium-Glass Laser with a Second-Harmonic Converter

Abstract

Heat dissipation is one of the most important issues for the reliability of electronic equipment. Boiling can be a very efficient heat transfer mechanism when used to face with the electronic technology needs of efficient and compact heat sinks. Recently, cellular structured materials both stochastic and periodic, particularly open cell metal foams, have been proposed as possible enhanced surfaces to lower the junction temperatures at high heat fluxes. Up today, most of the research on metal foams only regards single phase flow, whereas the two phase flow is still almost unexplored. This paper presents an experimental study on the heat transfer of R134a during flow boiling inside a 5 PPI (Pores Per linear Inch) copper foam, which is 5 mm high, 10 mm wide and 200 mm long, and it is brazed on a 10 mm thick copper plate. The experimental measurements were carried out by imposing three different heat fluxes (50, 75, and 100 kW m -2 ) and by varying the refrigerant mass velocity between 50 and 200 kg m -2 s -1 and the vapour quality from 0.2 to 0.90, at constant saturation temperature (30°C). The effects of the refrigerant mass flow rate, heat flux and vapour quality on the heat transfer coefficient, dry out phenomenon, and pressure drop are studied.

Nonlinear optical conversion of Nd:glass laser multimode radiation into the second harmonic in KDP crystal

“…Nowadays, in many laser research centres, high-order optical harmonics of the fundamental radiation generated in nonlinear crystals are widely used in experiments on the interaction of laser radiation with matter. Commonly, these harmonics serve as both heating radiation and probing radiation in optical diagnostic methods [1][2][3][4]. The application of high-order harmonics as a heating radiation avoids the destruction of laser optical elements, which is caused by backward-going radiation reflected by the target (plasma) [3].…”

“…Commonly, these harmonics serve as both heating radiation and probing radiation in optical diagnostic methods [1][2][3][4]. The application of high-order harmonics as a heating radiation avoids the destruction of laser optical elements, which is caused by backward-going radiation reflected by the target (plasma) [3]. The results of experiments on the interaction of Nd:glass laser fundamental radiation and its high-order harmonics with plasma in most cases showed the advantages of shorter wavelength radiation [5,6].…”