We discuss the issues related to choosing the optimum type of passive shielding of scintillation detectors based on BGO, NaI(Tl), and stilbene crystals from the direct penetration of neutron ...radiation with an energy of 14.1 MeV that was emitted isotropically into a solid angle of 4π. A series of experimental measurements of the count-rate suppression factor that may be obtained for the indicated detectors through the use of various shielding filters comprising iron, lead, and borated polyethylene layers with a total thickness not exceeding 50 cm are conducted.
Following indirect-drive experiments which demonstrated promising performance for low convergence ratios (below 17), previous direct-drive simulations identified a fusion-relevant regime which is ...expected to be robust to hydrodynamic instability growth. This paper expands these results with simulated implosions at lower energies of 100 and 270 kJ, and ‘hydrodynamic equivalent’ capsules which demonstrate comparable convergence ratio, implosion velocity and in-flight aspect ratio without the need for cryogenic cooling, which would allow the assumptions of one-dimensional-like performance to be tested on current facilities. A range of techniques to improve performance within this regime are then investigated, including the use of two-colour and deep ultraviolet laser pulses. Finally, further simulations demonstrate that the deposition of electron energy into the hotspot of a low convergence ratio implosion through auxiliary heating also leads to significant increases in yield. Results include break even for 1.1 MJ of total energy input (including an estimated 370 kJ of short-pulse laser energy to produce electron beams for the auxiliary heating), but are found to be highly dependent upon the efficiency with which electron beams can be created and transported to the hotspot to drive the heating mechanism.
The staged Z-pinch (SZP) is a magnetoinertial fusion scheme, where a high-Z gas liner implodes onto a deuterium gas target. An accurate measurement of the initial mass distribution, both in the liner ...and target, is crucial to achieve the fusion-relevant conditions. This paper presents the characterization of a double-valve injector for the SZP experiment, performed on a test stand with interferometric and visible emission diagnostics. The injector produces an annular liner gas profile that is peaked at R L = 1.25 cm, has an average full width at half-maximum Δr L = 0.50 cm, and a mass density ρ L = 0.5-140 μg/cm 3 , which is adjusted by selecting the gas species between Ar and Kr, plenum pressure, and injection timing. The target gas density is centered on the axis, has a width Δr T = 0.80 cm, and a density ρ T = 0.3-30 μg/cm 3 . The molecular deuterium can be partially ionized and accelerated out of the injector with a velocity v z > 2 cm/μs by a coaxial plasma gun built into the injector.
Nuclear fusion is a potential source of carbon-free electricity with many concepts in development. The Portable and Adaptable Neutron Diagnostics for Advancing Fusion Energy Science (PANDA-FES) suite ...has been deployed since 2021 to measure neutron yield, energy, and spatiotemporal source location at two different Z-pinch fusion devices. This diagnostic can be used at a variety of facilities pursuing fusion in the magnetic, inertial, and magneto-inertial regimes. These different regimes have a wide range of time scales from less than 100 ns to a few <inline-formula> <tex-math notation="LaTeX">\mu</tex-math> </inline-formula>s, neutron yields from 10<inline-formula> <tex-math notation="LaTeX">^6</tex-math> </inline-formula> to 10<inline-formula> <tex-math notation="LaTeX">^{11}</tex-math> </inline-formula>, and noise environments. Neutron yield is measured through activation of <inline-formula> <tex-math notation="LaTeX">^{79}</tex-math> </inline-formula>Br and <inline-formula> <tex-math notation="LaTeX">^{89}</tex-math> </inline-formula>Y with calibrated detectors. Temporal, spatial, and energy dependence of neutrons is measured with scintillators coupled to photomultiplier tubes (PMTs). Experimental setups and data analysis methods have been developed for these conditions. Neutron yield, neutron energy anisotropy, and spatiotemporal evolution of the source have been measured.
A study of the inelastic scattering of neutrons with an energy of $14.1$~MeV
on the nuclei of oxygen, phosphorus and sulfur was carried out at the TANGRA
facility at JINR (Dubna). The purpose of the ...experiment was to refine existing
and obtain new data on the yields and angular distributions of $\gamma$-quanta
emitted by the studied nuclei as a result of neutron-induced nuclear reactions
using the tagged neutron method. Two types of detector systems were used to
register $\gamma$-quanta. The $\gamma$-ray yields were measured using a
high-purity germanium (HPGe) detector. The angular distributions of
$\gamma$-rays were obtained using a system of 18 scintillation detectors based
on bismuth germanite Bi$_{4}$Ge$_{3}$O$_{12}$ (BGO) located around the sample.
As a result of the studies carried out, the yields of two transitions for the
reaction of tagged neutrons with $^{16}$O, nine transitions for the reaction
with $^{31}$P, and nine transitions for the reaction with $^{32}$S were
measured for the first time. The angular anisotropy of the $\gamma$-radiation
accompanying the inelastic scattering of neutrons with an energy of $14.1$~MeV
on $^{31}$P nuclei was also measured for the first time.
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