Speaker
Description
Polarized fuels in a tokamak fusion reactor can increase the cross section by 50%, and the power gain of an ITER-scale fusion reactor by 75%. The question is: can polarized materials survive inside a hot fusion plasma for times long enough to reap these expected gains? An in−situ polarization survivability test in a tokamak plasma is planned to address this. In a recent proposal (see William Heidbrink's plenary talk), we plan to prepare polarized $^7$LiD pellets and $^3$He capsules for injection into a hot plasma in the DIII-D tokamak, using the D + $^3$He $\rightarrow$ α + p reaction as a test bed. The $^7$LiD pellets need to be precisely engineered with fusion specifications, irradiated with electron beams at ~185K to induce paramagnetic centers, and stored at 77K. A dilution refrigerator-based DNP polarizer suitable to the planned fusion experiment will be designed and built at Jefferson Lab. This device will load the pre-irradiated $^7$LiD pellets, at ~2mm in size, into a polarization chamber, polarize them with microwaves at ~7 Tesla and ~100 mK, and measure polarization of individual pellets before dispensing into a tokamak gas gun pellet injector. Details will be discussed.
