Properties of luminescence from laser-created bubbles in pressurized water

Abstract

The properties of the luminescence pulse from collapsing laser-created bubbles in pressurized water are studied for pressures between 0.25 and 15 bars. The duration of the light pulse is found to be linear in the maximum bubble size, but for a given bubble size it increases with the applied pressure p as p0.38. The number of photons emitted increases quadratically with the bubble size, and increases approximately linearly with pressure. The spectrum of the luminescence is blackbody in form, with a temperature that increases somewhat with pressure, from 8100 K at 1 bar to 9400 K at 10 bars. At higher pressures the blackbody temperature drops, but this is primarily due to the rapid onset above 10 bars of a fission instability, where the bubbles split into two just before the collapse point.

Experimental Determination of Temperatures in Spark Generated Bubbles Oscillating in Water

“…The usable spectral range of the photodiode is 320-1100 nm. An analysis of the optical spectra given in the literature showed that the maximum temperatures in spark-generated and laser-generated bubbles range 5800-8150 K [5,11,15,18]. Then, using the Wien and Planck Law, it can be verified that the spectral maxima of the optical radiation are within the photodiode bandpass, and that the prevailing part of the radiation is received by the detector.…”

“…Using Wien's Law, it can be calculated that the temperatures Θ M 1 ranged 6600-7700 K. Unfortunately, the sizes of the bubbles generated in these experiments are not available. Golubnichii et al [5] studied bubbles generated by an exploding wire technique, and found that the maximum in the spectrum of the optical radiation associated with the first optical pulse u 1 (t) lies approximately [5] (Go), [12] (Ba), [14] (BW), [15] (Br); these values are discussed at the end of this section. vol.…”

“…While they are traditionally associated with erosion damage [1,2], recent efforts have been aimed at medical applications, such as contrastenhancing in ultrasonic imaging [3] and shock wave lithotripsy [4]. Both spark-generated bubbles [2,[5][6][7][9][10][11] and laser-generated bubbles [1,8,[12][13][14][15][16][17][18] are very useful tools in experimental studies of free bubble oscillations.…”

“…However, it is very difficult to determine the temperatures in spark-generated and laser-generated bubbles experimentally. Until now, only a limited number of estimates based on spectral analysis of the light emitted from the bubbles have been reported, in [5,8,11,12,14,15]. The difficulties associated with temperature measurements have their origin in the fact that the temperature in a bubble interior varies very rapidly in the final stages of the contraction phase, and the emitted light used for spectral analysis therefore has the form of a very short flash of light.…”

Cavitation bubble dynamics in non‐Newtonian fluids

“…There have been several observations of the production of light from laser-induced cavitation bubbles collapsing in water [79][80][81][82]. An estimate of the interior bubble temperature at the moment of light emission can be obtained by fitting the spectra to a blackbody form, and in general this yields results of about 8000 K. An extension of these studies to investigate the effect of viscoelastic properties of the liquid surrounding the bubble on the characteristics of the luminescence is highly desirable for a better understanding of the cavitation phenomenon in non-Newtonian fluids and associated damage to nearby boundaries.…”