Tabletop Fusion Revisited
I do not think that it is possible for R. P. Taleyarkhan et al. (“Evidence for nuclear emissions during acoustic cavitation,” Research Articles, 8 March, p. [1868][1]) to have observed 2.5-MeV neutrons for the simple reason that the pulse-height threshold used in their experiment is greater than
Life cycle of cavitation bubble for the nuclear emission
The dynamical behavior of cavitation bubble for the nuclear emissions has been developed in detail. Adiabatic expanding process from the embryo to the critical size and the imploding shock wave process from the critical bubble to the core bubble, where high temperature and high density are generated, are discussed. The cleared key points are as follows: (1) Coupling efficiency between ultrasonic wave and the cavitation bubble. (2) Equations of motions for the bubble growth and the implosion. (3) Important roles of the wave front of imploding shock wave. (4) Thermo-physical structure of the shrunk, shock wave. (5) Energy balance and pressure balance of the system. (6) The probability of nuclear reactions in the hot bubble core. (7) Effect of the core structure on the photon emission loss and the thermal conduction loss. The conclusion is that the bubble fusion is believed to be possible only under the very limited and tight conditions. The ultimate hydrogen energy systems will be based upon the water splitting by the bubble fusion.
PULSE: a high-repetition-rate linac driver for x-ray FELs
We describe a staged concept for a linac-based freeelectron laser providing coherent tuneable VUV and soft X-ray output with pulse lengths down to 10 fs or less. Use of 1.3 GHz cryomodules operated with CW RF will allow flexible pulse patterns at potentially very high repetition rates up to 1 MHz. We consider the options for FELs that may be included in a facility of this type.