Prospects for Direct In Situ Tests of Polarization Survival in a Tokamak

Sandorfi, A. M.; D’Angelo, A.

doi:10.1007/978-3-319-39471-8_9

Cited by 3 publications

(10 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During this period of initial excitement, a favorable costbenefit estimate was carried out [11,12], assuming general projections regarding the possible cost of polarizing fuel (which in the light of subsequent developments are probably pessimistic [13]). Several polarization methods and many possible depolarization mechanisms were assessed, [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Polarized fusion and potential in situ tests of fuel polarization survival in a tokamak plasma

et al. 2023

View full text Add to dashboard Cite

The use of spin-polarized fusion fuels would provide a significant boost towards the ignition of a burning plasma. The cross section for D+T→ α+n, would be increased by 1.5 if the fuels were injected with parallel polarization. Furthermore, our simulations demonstrate additional non-linear power gains in large-scale machines such as ITER, due to increased alpha heating. Such benefits require the survival of spin polarizations for periods comparable to the particle confinement time. During the 1980s, calculations predicted that polarizations could survive a plasma environment, although concerns persisted regarding the cumulative impacts of wall recycling. In that era, technical challenges prevented direct tests and left the large scale fueling of a power reactor beyond reach. Over the last decades, this situation has dramatically changed. Detailed simulations of ITER have predicted negligible wall recycling in a high-power reactor, and recent advances in laser-driven sources project the capability of producing large quantities of ~100% polarized D and T. The remaining crucial step is an in-situ demonstration of polarization survival in a plasma. For this, we outline a measurement strategy using the isospin-mirror reaction, D+3He→ α+p. Polarized 3He avoids the complexities of handling tritium, while encompassing the same spin-physics. We evaluate two methods of delivering deuterium, using dynamically polarized Lithium-Deuteride (with vector polarization PV D of 70%) or frozen-spin Hydrogen-Deuteride (with PV D of 40%), together with a method of injecting optically-pumped 3He (with 65% polarization). Pellets of these materials all have long polarization decay times (~6 minutes for LiD at 2K, ~2 months for HD at 2K, and ~3 days for 3He at 77K), all far greater than a plasma shot in a research tokamak such as DIII-D. Both species can be propelled from a single cryogenic injection gun. We review plasma requirements and strategies for detecting polarization survival. Polarization alters both fusion yields and the angular distribution of fusion products, and each of these provides a potential signal. In this paper we simulate a selection of shots with similar characteristics in a future high-Tion H plasma, and find ratios of yields from shots with fuel spins parallel and antiparallel reaching 1.3 (HD+3He) to 1.6 (LiD+3He) over a wide range of poloidal angles. (A companion paper finds sensitivity to fusion product angular distributions as reflected in the pitch angles of protons and alphas reaching the plasma facing wall.)

show abstract

Section: Introductionmentioning

confidence: 99%

Polarized fusion and potential in situ tests of fuel polarization survival in a tokamak plasma

et al. 2023

View full text Add to dashboard Cite

show abstract

“…pellet Figure 7-7: A GDP pellet (1.8 mm in diameter and 0.014 mm in wall thickness) inside a glass tube with 3 mm inner diameter (left) and the permeation time constant measured by the HDice group at JLab (right) [18,204].…”

Section: Spin-polarized Fusion D-3 He In the Tokamakmentioning

confidence: 99%

“…deviation from 1 for a large range of wall locations. A systematic study in [18,204,205] showed that 4 shots in each spin direction are needed to reach a 5 significance if assuming a 8% systematic shot-to-shot variation. For reference, the typical neutron production rate varied less than 10% between shots for the past 2 1 D − 2 1 D fusion experiments at ion temperature 8 keV in the DIII-D tokamak [205].…”

Section: Spin-polarized Fusion D-3 He In the Tokamakmentioning

confidence: 99%

“…For reference, the typical neutron production rate varied less than 10% between shots for the past 2 1 D − 2 1 D fusion experiments at ion temperature 8 keV in the DIII-D tokamak [205]. [18,204,205].…”

Section: Spin-polarized Fusion D-3 He In the Tokamakmentioning

confidence: 99%

“…If the reacting D-T system has a total angular momentum =3/2 and even parity, the excited state can be formed with high probability and the fusion occurs; otherwise the reaction cannot happen in principle and in reality the probability is two orders smaller in magnitude. For the typical fusion reactors at the keV level, the reaction is dominated by the s-wave process, so the angular momentum must be supplied by the spin of D Assuming the field is along the direction, the nuclear cross section for D+T−→ +n averaged over all possible spin orientations of D and T can be approximated as [18,204]…”

Section: Polarization Evolution Over Timementioning

confidence: 99%

See 2 more Smart Citations

The Proton Spin Structure Function g2 at Low Q2 and Applications of Polarized 3He

Liu

View full text Add to dashboard Cite

Since the Stern-Gerlach experiment in 1922, spin has had major implications on practically almost all areas of modern physics. Quantum chromodynamics (QCD) is the fundamental theory that describes strong interaction in terms of quark and gluon degrees of freedom. While QCD has been well tested in the high-energy regime, it is still unsolved in the low-energy, non-perturbative regime. With developments in polarized beam and polarized target technologies, spin offers a unique tool to probe the internal structure of nucleons and non-perturbative QCD dynamics. The polarization techniques developed for these fundamental nuclear physics study also bring new impulses to the idea of polarized fusion, in which spin-polarized deuterium and tritium (D-T) fuel in a tokamak reactor would provide a boost to the fusion rate. This thesis consists of three topics based on spin physics. The first topic is the Jefferson Lab (JLab) Hall A E08-027 (2) experiment performed with the polarized electron beam scattering off a polarized ammonia target to obtain the proton spindependent structure function g 2 in the low momentum transfer region (0.02 < Q 2 < 0.2 GeV 2). The measured data will provide a benchmark test of Chiral Perturbation Theory (PT) calculations in the non-perturbative region by extracting the generalized longitudinal-transverse polarizability , and help test the Burkhardt-Cottingham Sum Rule at low Q 2. This thesis will discuss the physics motivation, data analysis, and preliminary results from the E08-027 experiment in Chapters 2−5. The second topic is focused on the JLab polarized 3 He target, which is essential for the neutron spin structure study. Progress on the upgrade of this target for the JLab 12 GeV program will be presented in Chapter 6. The final topic is an application of such polarization techniques in thermonuclear fusion. A direct test of spin-polarized fusion was proposed for the DIII-D tokamak in San Diego using the isospin mirror reaction D-3 He. Preliminary results on the polarized 3 He performance in inertial confinement fusion (ICF) polymer pellets will be presented in Chapter 7.

show abstract

Polarized fuel for controlled thermonuclear fusion

Bartalucci

2017

Nuclear Instruments and Methods in Physics Research Section B:

View full text Add to dashboard Cite

Prospects for Direct In Situ Tests of Polarization Survival in a Tokamak

Cited by 3 publications

References 23 publications

Polarized fusion and potential in situ tests of fuel polarization survival in a tokamak plasma

Polarized fusion and potential in situ tests of fuel polarization survival in a tokamak plasma

The Proton Spin Structure Function g2 at Low Q2 and Applications of Polarized 3He

Polarized fuel for controlled thermonuclear fusion

Contact Info

Product

Resources

About