Speaker
Mr
Heinrich Hora
(Australia)
Description
Sauerbrey’s measurement [1] of ultrahigh acceleration of plasma blocks by 10^{20} cm/s^2 with ps laser pulses at very high intensity – confirmed by Földes et al. [2] – are 10,000 times higher than any acceleration with ns laser pulses. At ns, thermal pressure with losses and delays dominates the interaction, while the ps case is dominated by the instantly acting nonlinear (ponderomotive) force. The ps acceleration of 10^{20} cm/s^2 was theoretically and numerically predicted in 1978 [3] (see p. 179). The mechanism is different from electron acceleration in vacuum, first derived against preceding knowledge 1988 [4] as a nonlinear interaction process, and is different from acceleration of ion beams due to relativistic self-focusing [5].
Based on the measurements [1,2] the mechanism of the ps acceleration in contrast to that with ns pulses can now be understood as the non-thermal >99% efficient transfer of optical energy into macroscopic motion of the irradiated electron cloud in the space charge neutral plasma, where the inertia is determined by the cloud of the attracted ions. The sufficient small Debye length is essential in the high density plasma blocks. It is not trivial to distinguish the acceleration mechanisms of electrons in vacuum [4] of ion beams up to GeV [5] and that of space charge quasi-neutral plasma blocks [6] which were mostly interrelated and rather complicated. The clarification is shown how the block acceleration with full agreement between measurements [1] and the nonlinear force theory [6] led now to realize the fundamental difference to the thermokinetic processes with ns pulses. This is guided by the measurements of the ultrahigh block accelerations with consequences to a new scheme of fast ignition of laser fusion [7].
[1] Sauerbrey R 1996, Physics of Plasmas 3: 4712
[2] Földes I B, Bakos J S, Gal, K. et al. Laser Physics 10: 264
[3] Hora H 1981 Physics of Laser Driven Plasmas. New York: John Wiley
[4] Hora H 1988 Nature 333: 337; Hora H, Hoelss M, Scheid W et al. 2000 Laser & Part. Beams 18: 135
[5] Hora H 1975 J. Opt. Soc. Am. 65: 228; Cicchitelli et al. 1990 Phys. Rev. A41: 3727; Häuser T et al. 1992 Phys. Rev. A45: 1278
[6] Hora H. Laser & Part. Beams 2012 doi:10.1017/S0263034611000784
[7] Hora H, Miley G H et al. Energy & Environm. Science 3, 479
Collaboration (if applicable, e.g., International Tokamak Physics Activities)
International ICF Cooperation about Nonlinear Force Driven Plasma Blocks
Country or International Organization of Primary Author
Australia
Primary author
Mr
Heinrich Hora
(Australia)
Co-authors
Prof.
George H. MILEY
(Department of Nuclear, Plasma and Radiological Engineering, University of Illinois,)
Prof.
Istvan FÖLDES
(Wigner Research Center, Institute for Particle and Nuclear Physics Association EURATOM)
Prof.
PARASKEVAS lalousis
(Institute of Electronic Structure and Laser FORTH, Heraklion, Greece)
Prof.
Savros MOUSTAIZIS
(Technical University of Crete, Science Department, 73100 Chania, Crete, Greece)
Prof.
Xiantu HE
(Institute of Applied Physics and Computation Mathematics, Beijing, China)
Dr
Xiaoling Yang
(Department of Nuclear, Plasma and Radiological Engineering, University of Illinois,)
