Energy Concentrating Phenomena: From Sonoluminescence to Crystal Fusion

COFFEE_KLATCH · Invited

Abstract

Fluids and solids that are driven off equilibrium do not relax smoothly to equilibrium. Instead they display a wide range of energy focusing phenomena. In sonoluminescence (SL) a pulsating bubble concentrates the ambient acoustic energy density by 12 orders of magnitude to create picosecond flashes of broadband ultraviolet light. At the minimum bubble radius where the contents have been compressed to their van der Waals hard core the acceleration exceeds 10$^{11 }$g and a Mega-Bar level shock wave is emitted into the surrounding fluid. For single bubbles driven at 30 kHz SL is nature's smallest blackbody. At 1 MHz the spectrum resembles Bremsstrahlung from a transparent plasma with a temperature $\sim $1 MK and a nanometer radius. Whether cavitating systems will reach energy densities that initiate thermonuclear fusion is an open question. Ferroelectric crystals, however, can be configured to create nuclear fusion in a palm-sized apparatus. When the temperature of a ferroelectric crystal [e.g. Lithium Tantalate] is slightly varied, electrons are expelled with energies that can exceed 100 keV. By configuring the crystal surface with a field ionization tip, pyroelectricity can be used to generate and accelerate ions to energies where nuclear fusion occurs. Hoped-for applications range from miniature x-ray devices to neutron cameras to ion thrusters. In seeking to improve these devices one faces the question: what physics processes limit the spontaneous polarization [and resulting internal field] that can be produced with a ferroelectric crystal? For $\sim $50 years Lithium Niobate has exhibited the highest ratio of spontaneous polarization to dielectric constant. Why haven't superior materials been discovered? Is there a fundamental limit set by the laws of physics?

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Authors

  • Seth Putterman

    Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA, Department of Physics, Arizona State University, Tempe, AZ 85287, USA, College of Optical Sciences, University of Arizona, Colorado State University, University of Virginia, Auburn University, Northern Kentucky University, Utah Valley State College, Brigham Young University, Arizona State University, University of Amsterdam, New Mexico State university, University of Minesota, Pulse Field Facility, NHMFL, LANL, NM, Institute of Physics ASCR , Czech Republic, University of Minesota-Twin City, New Mexico State University, Director, Advanced Photon Source, Argonne National Lab, Australian Synchotron Source, Advanced Photon Source, Argonne National Lab, University of Arizona, U.S. Naval Research Laboratory, Wellesley College, Observatoire de Paris, France, Freie Universitat Berlin, Florida State Univ., Univ. Sci. Tech. China, Iowa State University, Lawrence Livermore National Laboratory, Mahabad Azad University, Carnegie Mellon University, Tempe Preparatory Academy, University of California, Los Angeles