排序方式: 共有23条查询结果,搜索用时 187 毫秒
1.
Bennett GR Cuneo ME Vesey RA Porter JL Adams RG Aragon RA Caird JA Landen OL Rambo PK Rovang DC Ruggles LE Simpson WW Smith IC Wenger DF 《Physical review letters》2002,89(24):245002
An inertial-confinement-fusion (ICF) concept using two 60-MA Z pinches to drive a cylindrical hohlraum to 220 eV has been recently proposed. The first capsule implosions relevant to this concept have been performed at the same physical scale with a lower 20-MA current, yielding a 70+/-5 eV capsule drive. The capsule shell shape implies a polar radiation symmetry, the first high-accuracy measurement of this type in a pulsed-power-driven ICF configuration, within a factor of 1.6-4 of that required for scaling to ignition. The convergence ratio of 14-21 is to date the highest in any pulsed-power ICF system. 相似文献
2.
Cuneo M.E. Lockner T.R. Tisone G.C. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(5):800-813
The refractive index gradient (RING) diagnostic described uses a fast, silicon, photodiode quadrant detector with a differential amplifier to temporally detect the refraction of a CW laser by transient discharges or expansions of vapor, gas, or plasma. The method is a local one-dimensional time-resolved, quantitative, species-discriminating (i.e., atoms or electrons) Schlieren technique. The diagnostic is easy to field, sensitive (the minimum deflection angles detectable are ≈0.3 μrad), and fast (risetime=11±1 ns). Circuit design, performance, and diagnostic theory are discussed. To illustrate the utility of this technique, examples of measurements on LEVIS (laser evaporation ion source), a laser-produced, active, lithium ion source, are given. Measured properties include vapor/plasma production thresholds, expansion velocities, and time-resolved gradient and density spatial profiles. Comparisons of the RING results with measurements using a Faraday cup and a double-floating Langmuir probe are presented 相似文献
3.
Haines NR VanZanten AN Cuneo AA Miller JR Andrews WJ Carlson DA Harrington RM Kiefer AM Mason JD Pigza JA Murphree SS 《The Journal of organic chemistry》2011,76(19):8131-8137
2,4-Disubstituted furans are prepared by treating 2,3-dibromo-1-phenylsulfonyl-1-propene (DBP, 2) with 1,3-diketones under basic conditions. The furan-forming step involves a deacetylation, and the selectivity of this process depends upon the steric demand of the R group. The substituent in position 4 is elaborated by reaction of sulfonyl carbanions with alkyl halides, acyl halides, and aldehydes. Oxidative or reductive desulfonylation produces the 2,4-disubstituted furans in 60-92% yield. This strategy has been used to prepare rabdoketone A (12) and the naturally occurring nematotoxic furoic acid 13. 相似文献
4.
Sinars DB Lemke RW Cuneo ME Lebedev SV Waisman EM Stygar WA Jones B Jones MC Yu EP Porter JL Wenger DF 《Physical review letters》2008,100(14):145002
Short-implosion-time 20-mm diameter, 300-wire tungsten arrays maintain high peak x-ray powers despite a reduction in peak current from 19 to 13 MA. The main radiation pulse on tests with a 1-mm on-axis rod may be explained by the observable j x B work done during the implosion, but bare-axis tests require sub-mm convergence of the magnetic field not seen except perhaps in >1 keV emission. The data include the first measurement of the imploding mass density profile of a wire-array Z pinch that further constrains simulation models. 相似文献
5.
We consider networks of massive particles connected by non-linear springs. Some particles interact with heat baths at different temperatures, which are modeled as stochastic driving forces. The structure of the network is arbitrary, but the motion of each particle is 1D. For polynomial interactions, we give sufficient conditions for Hörmander’s “bracket condition” to hold, which implies the uniqueness of the steady state (if it exists), as well as the controllability of the associated system in control theory. These conditions are constructive; they are formulated in terms of inequivalence of the forces (modulo translations) and/or conditions on the topology of the connections. We illustrate our results with examples, including “conducting chains” of variable cross-section. This then extends the results for a simple chain obtained in Eckmann et al. in (Commun Math Phys 201:657–697, 1999). 相似文献
6.
Hanson D.L. Cuneo M.E. McKay P.F. Coats R.S. Rosenthal S.E. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(5):831-839
Initial experiments to investigate coupling of the four-stage HELIA linear-induction accelerator to a uniformly insulated applied-B ion diode in planar extraction geometry are reported. Results describing the efficient operation of an applied-B extraction ion diode coupled to the HELIA linear induction accelerator operated in positive polarity are reported. Operation of a close-coupled, undermatched, applied-B diode on HELIA was consistent with magnetically insulated transmission line (MITL) electron flow intermediate between locally emitted flow and generalized flow, rather than with full-gap flow. Peak ion coupling efficiencies of 60-70% and peak ion power levels of 0.3-0.4 TW have been achieved 相似文献
7.
Vesey RA Cuneo ME Bennett GR Porter JL Adams RG Aragon RA Rambo PK Ruggles LE Simpson WW Smith IC 《Physical review letters》2003,90(3):035005
Simulations of a double Z-pinch hohlraum, relevant to the high-yield inertial-confinement-fusion concept, predict that through geometry design the time-integrated P2 Legendre mode drive asymmetry can be systematically controlled from positive to negative coefficient values. Studying capsule elongation, recent experiments on Z confirm such control by varying the secondary hohlraum length. Since the experimental trend and optimum length are correctly modeled, confidence is gained in the simulation tools; the same tools predict capsule drive uniformity sufficient for high-yield fusion ignition. 相似文献
8.
Sinars DB Cuneo ME Yu EP Bliss DE Nash TJ Porter JL Deeney C Mazarakis MG Sarkisov GS Wenger DF 《Physical review letters》2004,93(14):145002
We present the first comprehensive study of high wire-number, wire-array Z-pinch dynamics at 14-18 MA using x-ray backlighting and optical shadowgraphy diagnostics. The cylindrical arrays retain slowly expanding, dense wire cores at the initial position up to 60% of the total implosion time. Azimuthally correlated instabilities at the array edge appear during this stage which continue to grow in amplitude and wavelength after the start of bulk motion, resulting in measurable trailing mass that does not arrive on axis before peak x-ray emission. 相似文献
9.
Cuneo ME Vesey RA Porter JL Bennett GR Hanson DL Ruggles LE Simpson WW Idzorek GC Stygar WA Hammer JH Seamen JJ Torres JA McGurn JS Green RM 《Physical review letters》2002,88(21):215004
A double Z pinch driving a cylindrical secondary hohlraum from each end has been developed which can indirectly drive intertial confinement fusion capsule implosions with time-averaged radiation fields uniform to 2%-4%. 2D time-dependent view factor and 2D radiation hydrodynamic simulations using the measured primary hohlraum temperatures show that capsule convergence ratios of at least 10 with average distortions from sphericity of /r200 MJ. 相似文献
10.
Bennett GR Herrmann MC Edwards MJ Spears BK Back CA Breden EW Christenson PJ Cuneo ME Dannenburg KL Frederick C Keller KL Mulville TD Nikroo A Peterson K Porter JL Russell CO Sinars DB Smith IC Stamm RM Vesey RA 《Physical review letters》2007,99(20):205003
On the first inertial-confinement-fusion ignition facility, the target capsule will be DT filled through a long, narrow tube inserted into the shell. microg-scale shell perturbations Delta m' arising from multiple, 10-50 microm-diameter, hollow SiO2 tubes on x-ray-driven, ignition-scale, 1-mg capsules have been measured on a subignition device. Simulations compare well with observation, whence it is corroborated that Delta m' arises from early x-ray shadowing by the tube rather than tube mass coupling to the shell, and inferred that 10-20 microm tubes will negligibly affect fusion yield on a full-ignition facility. 相似文献