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211.
Fast ignition by intense laser-accelerated proton beams 总被引:12,自引:0,他引:12
Roth M Cowan TE Key MH Hatchett SP Brown C Fountain W Johnson J Pennington DM Snavely RA Wilks SC Yasuike K Ruhl H Pegoraro F Bulanov SV Campbell EM Perry MD Powell H 《Physical review letters》2001,86(3):436-439
The concept of fast ignition with inertial confinement fusion (ICF) is a way to reduce the energy required for ignition and burn and to maximize the gain produced by a single implosion. Based on recent experimental findings at the PETAWATT laser at Lawrence Livermore National Laboratory, an intense proton beam to achieve fast ignition is proposed. It is produced by direct laser acceleration and focused onto the pellet from the rear side of an irradiated target and can be integrated into a hohlraum for indirect drive ICF. 相似文献
212.
Zweiback J Smith RA Cowan TE Hays G Wharton KB Yanovsky VP Ditmire T 《Physical review letters》2000,84(12):2634-2637
Recent experiments on the interaction of intense, ultrafast laser pulses with large van der Waals bonded clusters have shown that these clusters can explode with substantial kinetic energy. By driving explosions in deuterium clusters with a 35 fs laser pulse, we have accelerated ions to sufficient kinetic energy to produce DD nuclear fusion. By diagnosing the fusion yield through measurements of 2.45 MeV fusion neutrons, we have found that the fusion yield from these exploding clusters varies strongly with the cluster size, consistent with acceleration of deuterons via Coulomb explosion forces. 相似文献
213.
Velocity fluctuations in a fluidized suspension of particles are investigated using two new ultrasonic correlation spectroscopies: diffusing acoustic wave spectroscopy and dynamic sound scattering. These techniques probe both the local strain rate and rms velocity of the particles, providing important information about the spatial extent of velocity correlations. Our results demonstrate the power of these techniques to probe particle dynamics of fluidized suspensions, and suggest that the velocity correlations are essentially independent of Reynolds numbers for Re(p)<1. 相似文献
214.
Zweiback J Cowan TE Smith RA Hartley JH Howell R Steinke CA Hays G Wharton KB Crane JK Ditmire T 《Physical review letters》2000,85(17):3640-3643
Exploiting the energetic interaction of intense femtosecond laser pulses with deuterium clusters, it is possible to create conditions in which nuclear fusion results from explosions of these clusters. We have conducted high-resolution neutron time-of-flight spectroscopy on these plasmas and show that they yield fast bursts of nearly monochromatic fusion neutrons with temporal duration as short as a few hundred picoseconds. Such a short, nearly pointlike source now opens up the unique possibility of using these bright neutron pulses, either as a pump or a probe, to conduct ultrafast studies with neutrons. 相似文献
215.
Bernard S.W. Dawson Glenda F. Parker Faye J. Cowan May C. Croucher Sung O. Hong Nigel H.O. Cummins 《Analytica chimica acta》1990
Accurate analysis for preservatives in treated timber is an integral part of quality assurance in the New Zealand timber preservation industry. The continued high volume use of boron-treated timber has highlighted the requirement for reliable methods to determine boron-containing preservatives in timber. Several aspects of a leaching-titration method are discussed in an effort to validate and standardize laboratory analysis of samples for the timber preservation industry. Steam volatility was found not to be a problem. The limit of detection was 0.007% (w/w) H3BO3 and the relative standard deviation of 50 replicate analyses was 2.2%. Statistical outliers and stragglers were identified by Cochran's test. The precision data (repeatability and reproducibility) from an interlaboratory determination of boric acid in timber were 0.0133–0.0273 and 0.0194–0.0535% H3BO3, respectively, over six concentration levels. Recommendations for maintaining active quality assurance programmes are made. 相似文献
216.
M. Baubillier I.J. Bloodworth G.J. Bossen A. Burns J.N. Carney C.A. Cowan G.F. Cox U. Dore Ph. Gavillet J.B. Kinson F. Levy P.F. Loverre H. McCann M. MacDermott P.J. Negus B.H. Oh M. Pratap R. Zitoun 《Physics letters. [Part B]》1979,89(1):131-135
Backward production of ω(1670) is observed in the reactions K?p→φ+φ?ω0Λ0 and K?p→φ+φ?φ0φ0 for |U'Λ|<1.0 GeV2. The cross section for the ω(1670) →φ+φ?ω0 decay mode is 1.90±0.35 μb for 8.25 GeV/c incident K?. Evidence is presented for the importance of the sequential decay, ω(1670) → Bφ → ωφφ with a branching ratio ω(1670) → Bφ/all ω(1670) → ωφφ=1.0±0.250.00. 相似文献
217.
A hologram has been made using a surface plasmon resonance wave as the reference beam. The surface wave was stimulated on a 1200-line/mm aluminum reflection grating that was coated with a thin layer of high resolution photographic emulsion. Experimental results are presented. 相似文献
218.
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Patel PK Mackinnon AJ Key MH Cowan TE Foord ME Allen M Price DF Ruhl H Springer PT Stephens R 《Physical review letters》2003,91(12):125004
A new technique is described for the isochoric heating (i.e., heating at constant volume) of matter to high energy-density plasma states (>10(5) J/g) on a picosecond time scale (10(-12)sec). An intense, collimated, ultrashort-pulse beam of protons--generated by a high-intensity laser pulse--is used to isochorically heat a solid density material to a temperature of several eV. The duration of heating is shorter than the time scale for significant hydrodynamic expansion to occur; hence the material is heated to a solid density warm dense plasma state. Using spherically shaped laser targets, a focused proton beam is produced and used to heat a smaller volume to over 20 eV. The technique described of ultrafast proton heating provides a unique method for creating isochorically heated high-energy density plasma states. 相似文献