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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 40g/cm3 to 7g/cm3). 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.
Bibliographical note© 2022 authors.
This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreements No. 633053 and No. 101052200—EUROfusion). Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. The involved teams have operated within the framework of the Enabling Research Projects No. AWP17-ENR-IFE-CEA-02, ‘‘Towards a universal Stark-Zeeman code for spectroscopic diagnostics and for integration in transport codes,” and No. AWP21-ENR-IFE.01.CEA, “Advancing shock ignition for direct-drive inertial fusion.”
G.P.-C. acknowledges funding from the French Agence Nationale de la Recherche (No. ANR-10-IDEX-03-02 and No. ANR-15-CE30-0011), the Conseil Règional Aquitaine (INTALAX), and the Spanish Ministry of Science and Innovation through the Margarita Salas funding program. C.V. and V.O.-B. acknowledge support from the LIGHT S&T Graduate Program (PIA3 Investment for the Future Program, No. ANR-17-EURE-0027). F.S.-V. acknowledges funding from The Royal Society (UK) through a University Research Fellowship. This study has received financial support from the French State in the framework of the Investments for the Future programme IdEx Université de Bordeaux/GPR LIGHT. This material is based upon work supported by the DOE Office of Science Grant No. DE-SC0022250. The work has also been supported by Research Grant No. CEI2020-FEI02 from the Consejería de Economía, Industria, Comercio y Conocimiento del Gobierno de Canarias and by Research Grant No. PID2019-108764RB-I00 from the Spanish Ministry of Science and Innovation.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344. This document was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor Lawrence Livermore National Security, LLC, nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or Lawrence Livermore National Security, LLC. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or Lawrence Livermore National Security, LLC, and shall not be used for advertising or product endorsement purposes.
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