Prof. Xiangdong Wei 
Jefferson Laboratory

Abstract

As part of a Spin Polarized Fusion (SPF) program, polarized 7 LiD pellets are being developed at Jefferson Lab (JLAB) for testing the survivability of nuclear polarization in a ∼100 million Kelvin fusion plasma. With polarized fuels in a tokamak, the cross section can increase by 50%, and the power gain of a large-scale fusion reactor, such as ITER, by 80%. However, this power gain can only be realized if the fuel polarizations survive for periods comparable or longer than the particle confinement times (at least times on the order of seconds). Recently, the initial phase of an in-situ demonstration of polarization survivability in a tokamak plasma, proposed by the SPF collaboration, has been funded to answer this crucial question. We are preparing polarized 7 LiD pellets and 3 He capsules for injecting into the plasma at the DIII-D tokamak of the DOE National Fusion Facility in San Diego, using the isospin-mirror reaction, D+ 3 He→a+p; this will mimic the standard D+T→a+n fusion process without introducing tritium. At JLAB, 7 LiD pellets made with fusion specifications will be irradiated with electron beams at the newly built Irradiation Beamline at the CEBAF Injector; irradiations will be carried out at ∼185K to induce paramagnetic centers, and then stored at 77K. A DNP polarizer, with a pellet handling system suitable to manipulate single 7LiD cylinders of ∼1.5mm in size, and capable of polarizing many pellets simultaneously at ∼7 Tesla and ∼100 mK, is being designed based on a commercial dry dilution
refrigerator. In parallel, efforts are also underway at UVA for building a 3He polarizer, at ORNL for developing 2 fuel injection guns, at UC-Irvine for detecting fusion products and at DIII-D to prepare for the SPF experiment. In phase −II, all devices will be integrated and commissioned. The SPF experiment at DIII-D will be carried out in phase − III.

 
Brief bio: 

Wei, Xiangdong earned BS from Peking University in 1982, MS and PhD from Syracuse in 1992 and 1994, respectively. His early research focused on polarized HD and D2 targets for ICF and for nuclear physics. After developing the polarized HD target for LEGS at Brookhaven Lab (BNL) as a Postdoctoral Fellow at Syracuse, he joined BNL in 1998 and was subsequently promoted to Associate Physicist in 2000 and Physicist in 2003. In 2008, he moved to Jefferson Lab (JLab) as a Staff Scientist, and later became the deputy leader of HDice group. He has been a leading figure in the polarized HD target research, both at BNL and JLab. He designed and optimized most target equipment for the SPHICE and HDice programs. Besides nuclear physics, his research interests include spin-polarized fusion. Currently he focuses on the polarized LiD targets. He manages all targets used in Hall-B department at JLab, and leads a team to prepare polarized 7LiD pellets for studying the polarization survivalability in fusion plasma at the DIII-D National Fusion Facility. He has more than 35 years experiences on cryogenic systems (especially milli-Kelvin dilution refrigerator with high magnetic field), NMR spectrometry, superconducting magnets, and polarization of solid HD and D2. He has authored over 140 scientific papers. He has served on DOE experiment-review committee and facility User Board, and on proposal review panels for the German Research Association, and other review panels.