Light-induced heat and mass transfer in a single-component gas in a capillary

Heat and mass transfer in gases due to pressure and temperature gradients in a laser radiation field

“…The pressure gradient opposite to the propagation of radiation appears in the capillary. According to [5], a surface light-induced drift and the heat flux in the whole range of Knudsen numbers are directed opposite to each other. In closed insulated system this leads to the establishment of oppositely pressure and temperature gradients in the free molecular regime.…”

“…Gradients reach their maximum values at 7 , 0 v k . In the exact resonance at 0 light-induced pressure and temperature gradients are not available, as the LID and LIHT [1,5]. Gradients directions are determined by the signs of detuning from the center of the absorption line and the difference of the accommodation coefficients.…”

“…Stimulated transitions and radioactive decay of the excited levels lead to the exchange of atoms between excited and unexcited components. It leads to the appearance of light-induced heat and mass flows of excited and unexcited particles in the channel and, under certain conditions, there are a drift of the gas as a whole (LID) and heat flux (LIHT) [5]. Light-induced currents are superimposed on the flows caused by pressure and temperature gradients that lead to the emergence of new cross-effects.…”

Light-induced cross transport phenomena in a single-component gas

“…If a uniform gas pressure was maintained along the capillary tube, a stationary temperature gradient would occur provided LIHT is compensated by the ordinary heat flux proportional to the temperature gradient. Note that LIHT is caused by the difference between the accommodation coefficients and the col lision cross sections of excited and unexcited particles, as for the transfer of the translational energy of parti cles [3], and also includes the excitation energy flux. In a closed heat insulated capillary, stationary pres sure and temperature gradients form as a result of the interaction of LID, the Poiseuille flow, thermal creep, LIHT, ordinary heat flux, and isothermal heat transfer proportional to the pressure gradient (mechanocaloric flow) [5].…”

“…Light induced drift (LID) [1] and heat transfer (LIHT) [2,3] are known to appear in a gas during the selective absorption of optical radiation by molecules or atoms at certain velocities. Experimental recording of the LID rate is a complex technical problem.…”