Cylindrical implosion platform for the study of highly magnetized plasmas at Laser MegaJoule

G. Pérez-Callejo (1) , C. Vlachos (1) , C.A. Walsh (2) , R. Florido (3) , M. Bailly-Grandvaux (4) , X. Vaisseau (5) , F. Suzuki-Vidal (6) , C. Mcguffey (7) , F.N. Beg (4) , P. Bradford (1) , V. Ospina-Bohórquez (1, 5, 8) , D. Batani (1) , D. Raffestin (1) , A. Colaïtis (1) , V. Tikhonchuk (1) , A. Casner (1, 9) , M. Koenig (10) , B. Albertazzi (10) , R. Fedosejevs (11) , N. Woolsey (12) , M. Ehret (13) , A. Debayle (5, 8) , P. Loiseau (5, 8) , A. Calisti (14) , S. Ferri (14) , J. Honrubia (15) , R. Kingham (6) , R.C. Mancini (16) , M.A. Gigosos (17) , J.J. Santos (1)

1 CELIA - Centre d'Etudes Lasers Intenses et Applications
2 LLNL - Lawrence Livermore National Laboratory
3 ULPGC - Universidad de las Palmas de Gran Canaria
4 UC San Diego - University of California [San Diego]
5 DAM/DIF - DAM Île-de-France
6 Theoretical Physics, Blackett Laboratory, Imperial College, Prince Consort Road
7 General Atomics [San Diego]
8 LMCE - Laboratoire Matière sous Conditions Extrêmes
9 CESTA - Centre d'études scientifiques et techniques d'Aquitaine
10 LULI - Laboratoire pour l'utilisation des lasers intenses
11 University of Alberta
12 University of York [York, UK]
13 Centros de Laseres Pulsados
14 PIIM - Physique des interactions ioniques et moléculaires
15 ETSI - Escuela Técnica Superior de Ingenieros de Telecomunicación [Madrid]
16 University of Nevada [Reno]
17 UVa - Universidad de Valladolid [Valladolid]

Investigating the potential benefits of the use of magnetic fields in inertial confinement fusion experiments has given rise to experimental platforms like the Magnetized Liner Inertial Fusion approach at the Z-machine (Sandia National Laboratories) or its laser-driven equivalent at OMEGA (Laboratory for Laser Energetics). Implementing these platforms at MegaJoule-scale laser facilities, such as the Laser MegaJoule (LMJ) or the National Ignition Facility (NIF), is crucial to reaching self-sustained nuclear fusion and enlarges the level of magnetization that can be achieved through a higher compression. In this paper, we present a complete design of an experimental platform for magnetized implosions using cylindrical targets at LMJ. A seed magnetic field is generated along the axis of the cylinder using laser-driven coil targets, minimizing debris and increasing diagnostic access compared with pulsed power field generators. We present a comprehensive simulation study of the initial B field generated with these coil targets, as well as two-dimensional extended magnetohydrodynamics simulations showing that a 5 T initial B field is compressed up to 25 kT during the implosion. Under these circumstances, the electrons become magnetized, which severely modifies the plasma conditions at stagnation. In particular, in the hot spot the electron temperature is increased (from 1 keV to 5 keV) while the density is reduced (from $40{\mathrm{g}/\mathrm{cm}}^3$ to $7{\mathrm{g}/\mathrm{cm}}^3$). We discuss how these changes can be diagnosed using x-ray imaging and spectroscopy, and particle diagnostics. We propose the simultaneous use of two dopants in the fuel (Ar and Kr) to act as spectroscopic tracers. We show that this introduces an effective spatial resolution in the plasma which permits an unambiguous observation of the B-field effects. Additionally, we present a plan for future experiments of this kind at LMJ.

Mots clés: nucleus: fusion; laser; plasma; cylinder; OMEGA; magnetization; experimental equipment; numerical calculations; hydrodynamics

Domaines: Physique Générale [physics.gen-ph]; Physique des Hautes Energies - Expérience [hep-ex]

G. Pérez-Callejo, C. Vlachos, C.A. Walsh, R. Florido, M. Bailly-Grandvaux, et al.. Cylindrical implosion platform for the study of highly magnetized plasmas at Laser MegaJoule. Physical Review E , 2022, 106 (3), pp.035206. ⟨10.1103/PhysRevE.106.035206⟩. ⟨hal-03635384⟩