Study on Au + U + Au sandwich Hohlraum wall for ignition targets

Abstract

In ignition targets designs, U or U based cocktail hohlraum are usually used because the Rosseland mean opacity of U is higher than for Au at the radiation temperature for ignition. However, it should be noted that the opacity of U is obviously lower than for Au when the radiation temperature falls into a low temperature region. Because the depth penetrated by radiation is only several micrometers under a 300eV drive, and also because there is a prepulse longer than 10 ns prepulse at temperatures lower than 170 eV in the radiation drive of ignition target designs. Therefore we propose an Au þ U þ Au sandwich hohlraum for ignition targets in this work. Compared to the cocktail, the sandwich not only remarkably simplifies the fabrication and uses less depleted U material, but also increases the albedo during the prepulse.

Uranium hohlraum with an ultrathin uranium–nitride coating layer for low hard x-ray emission and high radiation temperature

“…Based on the benefits in terms of preheating and asymmetry, we believe UN-coated depleted uranium is a promising material for the ignition hohlruam. Based on our previous study of the sandwich hohlraum wall of 0.1 μm Au + 5.0 μm U + 19.9 μm Au [19], we designed a novel wall composition of 0.1 μm UN + 5.0 μm U + 19.9 μm Au. Compared to the sandwich hohlruam of Au+U+Au applied in NIC, the UN+U+Au sandwich hohlraum can generate nearly the same radiation temperature but a lower hard x-ray fraction.…”

“…However, cocktail hohlraum has not been widely used due to the wall oxidization. The sandwich hohlraum recently applied in the National Ignition Campaign (NIC) has a sandwiched geometry of Au+U+Au [19]. The inner Au coating layer, which is 600 nm∼700 nm thick, can protect the middle U layer against oxidization [15,20].…”

An initial design of hohlraum driven by a shaped laser pulse

“…Hence, we can first use our 2D code LARED-H to obtain a primary radiation in a half hohlraum with a reasonable supposed size under the given laser pulse, and then use onedimensional code radiation hydrodynamic code of multigroups (RDMG) (Feng et al, 1999;Li et al, 2010) to obtain the wall albedo under the radiation. Figure 2 shows the temporal T r from LARED-H by taking R as 850 mm and L as 1450 mm, and the corresponding temporal albedo from RDMG.…”

“…Since the hohlraum target plays a key role in the study of indirect drive inertial fusion study, the experimental and theoretical target design, and simulation continuously attract extensive interests and efforts worldwide (Aleksandrova et al, 2008;Atzeni & Meyer-Ter-vehn, 2004;Borisenko et al, 2008;Bret & Deutsch, 2006;Chatain et al, 2008;Deutsch et al, 2008;Eliezer et al, 2007;Foldes & Szatmari, 2008;Hoffmann, 2008;Holmlid et al, 2009;Hora, 2007;Imasaki & Li, 2007;Koresheva et al, 2009;Li et al, 2010;Ramis et al, 2008;Rodriguez et al, 2008;Strangio et al, 2009;Winterberg, 2008;Yang et al, 2008). The optimal size of a hohlraum is a trade-off between the requirements for energy and power, and the need for symmetry and acceptable plasma filling.…”

Some recent studies on hohlraum physics

“…Here, we will present some of our recent studies on hohlraum energetic and hohlraum design, including studies on recent hohlraum physics experiments on SGIII prototype [5], Au + U + Au sandwich hohlraum for ignition target [6], and method of giving an initial design of hohlraum and driving laser to generate a required radiation for 2-D optimizations [7]. In addition, we have also obtained some interesting results on x-ray ablative shock waves [8] and proposed a novel method for simultaneously determining the maximum radiation temperature and M-band fraction inside a hohlraum by using the shock wave technology [9], which was presented by Yongsheng Li, et al, in this conference.…”