Targets intended to produce ignition on the National Ignition Facility are being simulated, and the simulations are used to set specifications for target fabrication. Recent design work has focused ...on refining designs that use 1.3 MJ of laser energy, with an ablator of Be(Cu) or CH(Ge). The mainline hohlraum design now has a He-H gas fill and a wall of U-Au layers. The emphasis in this paper is on changes in the requirements over the last year. Complete tables of specifications are regularly updated for all of the targets. All the specifications are rolled together into an error budget indicating adequate margin for ignition with all of the designs.
The ablation front Rayleigh Taylor hydroinstability growth dispersion curve for indirect-drive implosions has been shown to be dependent on the Richtmyer Meshkov growth during the first shock transit ...phase. In this paper, a simplified treatment of the first shock ablative Richtmyer-Meshkov (ARM) growth dispersion curve is used to extract differences in ablation front perturbation growth behavior as function of foot pulse shape and ablator material for comparing the merits of various ICF design option.
A multidimensional measurable criterion for central ignition of inertial-confinement-fusion capsules is derived. The criterion accounts for the effects of implosion nonuniformities and depends on ...three measurable parameters: the neutron-averaged total areal density (rhoR(n)(tot)), the ion temperature (T(n)), and the yield over clean (YOC=ratio of the measured neutron yield to the predicted one-dimensional yield). The YOC measures the implosion uniformity. The criterion can be approximated by chi=(rhoR(n)(tot))(0.8) x (T(n)/4.7)(1.7)YOC(mu)>1 (where rhoR is in g cm(-2), T in keV, and mu approximately 0.4-0.5) and can be used to assess the performance of cryogenic implosions on the NIF and OMEGA. Cryogenic implosions on OMEGA have achieved chi approximately 0.02-0.03.
Radiation-driven, low-adiabat, cryogenic DT layered plastic capsule implosions were carried out on the National Ignition Facility (NIF) to study the sensitivity of performance to peak power and drive ...duration. An implosion with extended drive and at reduced peak power of 350 TW achieved the highest compression with fuel areal density of ~1.3±0.1 g/cm2, representing a significant step from previously measured ~1.0 g/cm2 toward a goal of 1.5 g/cm2. Future experiments will focus on understanding and mitigating hydrodynamic instabilities and mix, and improving symmetry required to reach the threshold for thermonuclear ignition on NIF.
Description of the NIF Laser Spaeth, M. L.; Manes, K. R.; Kalantar, D. H. ...
Fusion science and technology,
02/2016, Letnik:
69, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The possibility of imploding small capsules to produce mini-fusion explosions was explored soon after the first thermonuclear explosions in the early 1950s. Various technologies have been pursued to ...achieve the focused power and energy required for laboratory-scale fusion. Each technology has its own challenges. For example, electron and ion beams can deliver the large amounts of energy but must contend with Coulomb repulsion forces that make focusing these beams a daunting challenge. The demonstration of the first laser in 1960 provided a new option. Energy from laser beams can be focused and deposited within a small volume; the challenge became whether a practical laser system can be constructed that delivers the power and energy required while meeting all other demands for achieving a high-density, symmetric implosion. The National Ignition Facility (NIF) is the laser designed and built to meet the challenges for study of high-energy-density physics and inertial confinement fusion (ICF) implosions. This paper describes the architecture, systems, and subsystems of NIF. It describes how they partner with each other to meet these new, complex demands and describes how laser science and technology were woven together to bring NIF into reality.
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