Measurement facility for the relative radiation energy density distribution for pulse-periodic lasers

We investigated the process of laser heat treatment of polished brass samples (36% zinc, containing a small amount of lead, which does not dissolve in the alloy and is in the form of inclusions, having micron and submicron size) by impacting to a series of 25 - 30 ultraviolet (UV) pulses of a Nd:YAG laser (third harmonic, wavelength λ = 355 nm, duration τ = 10 ns, pulse repetition rate f = 10 Hz, pulse energy density ~ 0.15 - 1.0 J/cm2) in the stationary spot mode. Copper and its alloys absorb up to 90% of the energy of this laser. It is found that the relaxation of the absorbed energy of laser radiation in the metal occurs nonuniformly. Defects in the metal structure such as grain boundaries and lead inclusions are visualized. Traces of crystallographic sliding appear inside some grains. With an increase in the number of impacting impulses, accumulation of damage is observed. A further increase in the radiation energy density leads to an aggravation of the observed phenomena.

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Ponderomotive pressure effects in laser driven high-temperature plasma flows

Journal of Plasma Physics ◽

10.1017/s0022377800023060 ◽

1981 ◽

Vol 25 (2) ◽

pp. 193-213 ◽

Cited By ~ 3

Author(s):

J. L. Bobin

Keyword(s):

High Temperature ◽

Mach Number ◽

Energy Density ◽

Density Ratio ◽

Radiation Energy ◽

Pressure Effects ◽

Initial State ◽

Temperature Plasma ◽

Radiation Energy Density ◽

Plasma Effects

Gasdynamical equations taking radiation energy density and ponderomotive pressure into account are investigated. Conditions for these quantities to be important are stated: low absorption, reflexion at cut-off. The density ratio in a discontinuity is studied as a function of ponderomotive pressure, absorbed intensity and Mach number in the initial state. Chapman–Jouguet conditions are defined. Compressive (R type) flows and rarefaction (D type) appear. The structure of the latter is discussed including plasma effects.

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Observational Constraints on the Lepton Asymmetry and Radiation Energy Density

10.1063/1.2870439 ◽

2008 ◽

Author(s):

L. A. Popa ◽

A. Vasile ◽

Livius Trache ◽

Sabin Stoica

Keyword(s):

Energy Density ◽

Radiation Energy ◽

Observational Constraints ◽

Radiation Energy Density ◽

Lepton Asymmetry

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Radiation Energy Density and Radiation Heat Flux in Small Rectangular Cavities

Journal of Heat Transfer ◽

10.1115/1.3449934 ◽

1972 ◽

Vol 94 (3) ◽

pp. 289-294 ◽

Cited By ~ 1

Author(s):

R. P. Caren

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Energy Density ◽

Classical Theory ◽

Radiant Energy ◽

Radiation Energy ◽

Radiant Heat ◽

Radiant Heat Transfer ◽

Radiation Heat ◽

Radiation Energy Density

The present paper investigates the impact of one or more small cavity dimensions on the radiation energy density and radiation heat flux in rectangular metallic cavities. The emphasis of the present analysis is the exact treatment of the modal structure of the electromagnetic field in a small cavity in determining the properties of the thermal radiation field in the cavity. The excitation spectrum of the modes is assumed to be given by the Planck distribution function. The Poynting theorem is invoked in order to determine the radiative heat flux absorbed by the walls from the radiation in the cavity. Variation of the dimensions of the rectangular cavity allows the effects of cavity size and shape on the radiant energy density and radiant heat transfer to be assessed, particularly in several interesting limiting cases. It is found that significant deviations from the classical theory occur whenever any of the cavity dimensions satisfy the inequality lT ≤ 1 cm-deg K. It is further found that, when two or more of the cavity dimensions satisfy the above inequality, the radiant energy density and radiant heat transfer are significantly reduced in comparison to the results of classical theory. However, when only one dimension is limited, as in the case of a closely spaced parallel-surface geometry, the radiant energy density and radiant heat transfer are significantly increased compared to the classical theory.

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