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Fu, Changbo

Publications and source records attributed to Fu, Changbo.

4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

High-energy-density plasma in femtosecond-laser-irradiated nanowire-array targets for nuclear reactions

In this work, the high-energy-density plasmas (HEDP) evolved from joule-class-femtosecond-laser-irradiated nanowire-array (NWA) targets were numerically and experimentally studied. The results of particle-in-cell simulations indicate that ions accelerated in the sheath field around the surfaces of the nanowires are eventually confined in a plasma, contributing most to the high energy densities. The protons emitted from the front surfaces of the NWA targets provide rich information about the interactions that occur. We give the electron and ion energy densities for broad target parameter ranges. The ion energy densities from NWA targets were found to be an order of magnitude higher than those from planar targets, and the volume of the HEDP was several-fold greater. At optimal target parameters, 8% of the laser energy can be converted to confined protons, and this results in ion energy densities at the GJ/cm 3 level. In the experiments, the measured energy of the emitted protons reached 4 MeV, and the changes in energy with the NWA’s parameters were found to fit the simulation results well. Experimental measurements of neutrons from 2 H(d,n) 3 He fusion with a yield of (24 ± 18) × 10 6 /J from deuterated polyethylene NWA targets also confirmed these results.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Constraining self-interacting dark matter with the full dataset of PandaX-II

Self-interacting dark matter (SIDM) is a leading candidate proposed to solve discrepancies between predictions of the prevailing cold dark matter theory and observations of galaxies. Many SIDM models predict the existence of a light force carrier that mediates strong dark matter self-interactions. If the mediator couples to the standard model particles, it could produce characteristic signals in dark matter direct detection experiments. We report searches for signals of SIDM models with a light mediator using the full dataset of the PandaX-II experiment, basing on a total exposure of 132 tonne-days. No significant excess over background is found, and our likelihood analysis leads to a strong upper limit on the dark matter-nucleon coupling strength. We further combine the PandaX-II constraints and those from observations of the light element abundances in the early universe, and show that direct detection and cosmological probes can provide complementary constraints on dark matter models with a light mediator.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Measurements of D–D fusion neutrons generated in nanowire array laser plasma using Timepix3 detector

Here, we present results of the neutron detection in laser plasma experiment with CD2 nanowire target. A hybrid semiconductor pixel detector Timepix3 covered with neutron converters was using for the detection neutrons. D-D fusion neutrons were detected in a plastic converter through recoiled protons. Both the energy of recoiled protons and time-of-flight of neutrons (and thus their energy) were determined. We report (2.4±1.8) × 10 7 neutrons generated for 1 J of incoming laser energy. Furthermore, we proved that Timepix3 is suitable for difficult operational conditions in laser experiments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗