Energetic Cavitation Collapse Generates 3.2 Mbar Plasma with a 1.4 J Driver

Marc C. Ramsey, Robert W. Pitz
2013 Physical Review Letters  
A tabletop device uses 1.4 J to drive the symmetric collapse of a 1.8 mm radius vapor bubble in water at 22 bar. Single shot streak imaging reveals a stagnation plasma of 28 micron radius at over 12,000 K and an unprecedented pressure of 3.2 Mbar. Compared to sonoluminescence, the most commonly studied cavitation mechanism, this event is greater by factors of 30-40 in size, 1,000,000 in energy and 100 in stagnation pressure. This regime of high energy density has previously been accessible only
more » ... een accessible only in massive facilities with very low repetition rates. Energy focused by the spherical collapse of a cavitation bubble can generate thermodynamic extremes at stagnation [1] [2] [3] . This phenomenon is commonly studied in the context of single-bubble sonoluminescence (SBSL) [4] [5] [6] [7] , where a bubble of about 50 μm maximum radius is driven periodically by an ultrasonic standing wave of 1-2 bar in amplitude. Each collapse has about 50 nJ of kinetic energy and proceeds to roughly 1 μm radius before emitting a picosecond burst of light[8-10], with the stagnation state estimated at 1-60 kbar [11] [12] [13] and 10 4 -10 6 K[14-17]. However, the true stagnation mechanisms and state are debated [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] , and SBSL cannot be readily scaled for practical study or application. SBSL is subject to strict limitations in parameter space enumerated carefully by Brenner et. al.[6]. These stem from the fact that SBSL is fundamentally periodic; a single bubble oscillates in quasi-equilibrium, so all phases of the cycle must be stable. Above a certain threshold of stagnation energy density, the bubble always disintegrates on rebound due to the Rayleigh-Taylor inertial instability when the low density bubble interior accelerates the liquid [22] . Ultimately, the same limitation applies to variants of SBSL which
doi:10.1103/physrevlett.110.154301 pmid:25167272 fatcat:mzbgk6b26fbdzhl5s6qyazvjki