Abstract: The paper describes the operation features of plasma focus chambers using deuterium–tritium mixture. Handling tritium requires the use of sealed, vacuum-tight plasma focus chambers. In these chambers, there is an accumulation of the impurity gases released from the inside surfaces of the electrodes and the insulator while moving plasma current sheath inside chambers interacting with β-electrons generated due to the decay of tritium. Decay of tritium is also accompanied by the accumulation of helium. Impurities lead to a decreased yield of neutron emission from plasma focus chambers, especially for long term operation. The paper presents an option of absorption type gas generator in the chamber based on porous titanium, which allows to significantly increase the lifetime and shelf life of tritium chambers. It also shows the results of experiments on the comparison of the operation of sealed plasma focus chambers with and without the gas generator.
Abstract: Wuhan National High Magnetic Field Center (WHMFC) at Huazhong University of Science and Technology is one of the top-class research centers in the world, which can offer pulsed fields up to 90.6 T with different field waveforms for scientific research and has passed the final evaluation of the Chinese government in 2014. This paper will give a brief introduction of the facility and the development status of pulsed magnetic fields research at WHMFC. In addition, it will describe the application development of pulsed magnetic fields in both scientific and industrial research.
Abstract: Instead of praises from colleagues, the claim of observation of metallic hydrogen at 495 GPa by Dias and Silvera met much skepticism, and grew into a public debate at the International Conference on High-Pressure Science and Technology, AIRAPT26. We briefly review this debate, and extend the topic to show that this disputation could be an opportunity to benefit the whole high pressure community.
Abstract: The equation of states, diffusions, and viscosities of strongly coupled Fe at 80 and 240 eV with densities from 1.6 to 40 g/cm3 are studied by orbital-free molecular dynamics, classical molecular dynamics with a corrected Yukawa potential and compared with the results from average atom model. A new local pseudopotential is generated for orbital free calculations. For low densities, the Yukawa model captures the correct ionic interaction behavior around the first peak of the radial distribution function (RDF), thus it gives correct RDFs and transport coefficients. For higher densities, the scaled transformation of the Yukawa potential or adding a short range repulsion part to the Yukawa potential can give correct RDFs and transport coefficients. The corrected potentials are further validated by the force matching method.
Abstract: Relativistic electron beams driven by laser wakefield acceleration were utilized to produce ultrashort neutron sources. The experiment was carried out on the 38 fs, ∼0.5 J, 800 nm Ti:Sapphire laser in the 10 TW UT3 laser lab at University of Texas at Austin. The target gas was a high density pulsed gas jet composed of 90% He and 10% N2. The laser pulse with a peak intensity of 1.5 × 1018 W/cm2 interacted with the target to create a cylindrical plasma channel of 60 μm radius (FWHM) and 1.5 mm length (FWHM). Electron beams of ∼80 pC with the Gaussian energy distribution centered at 37 MeV and a width of 30 MeV (FWHM) were produced via laser wakefield acceleration. Neutron fluences of ∼2.4 × 106 per shot with hundreds of ps temporal length were generated through bremsstrahlung and subsequent photoneutron reactions in a 26.6 mm thick tungsten converter. Results were compared with those of simulations using EPOCH and GEANT4, showing agreement in electron spectrum, neutron fluence, neutron angular distribution and conversion rate.
Current Issue
Issue 6, November, 2022
ISSN2468-2047
eISSN2468-080X
CN51-1768/O4
Co Editors-in-Chief:Weiyan Zhang Michel Koenig Hokwang Mao
