Introduction

• V. Tikhonchuk

An advanced Shock Ignition scheme and the UK Programme for Laser Inertial Fusion Technology: UPLiFT

• R. H.H Scott

Laser Inertial Fusion Energy has the potential to provide clean, sustainable, and secure baseload electricity. The recent seminal fusion energy-gain result on the National Ignition Facility (NIF) has reinvigorated the quest to realize Inertial Fusion Energy (IFE). This talk will begin by providing an overview of Laser Inertial Fusion, the underlying physics and methodologies, and an overview of recent results. It will then go on to discuss innovative technologies and techniques that are more efficient than those employed on NIF and, hence, more suitable for power plants. These include energetically-efficient lasers, ‘Direct Drive’, ‘Shock Ignition’, and ‘Shock-Augmented Ignition’. Finally, we will discuss the perceived advantages and challenges of Laser Inertial Fusion Energy.

Progress toward laser fusion in Europe

• S. Le Pape

With the achievement of Ignition in 2022 on the National Ignition Facility (NIF), Inertial Confinement Fusion (ICF) is now envisioned as a clear contender for a decarbonized energy source. Nevertheless, Inertial Fusion Energy (IFE) is still years away and requires a significant effort by the European community to reach that goal. This talk will broadcast results from the European community to improve our basic understanding of key theoretical and experimental physics at play for IFE. Newly awarded EUROfusion projects on ICF will also be presented to the community. The first project investigates the use of foam as a path to IFE, and the second project uses a magnetic field to increase the fusion of yield. Finally, “Taranis,” a new French initiative towards IFE, will be portrayed. Taranis is a consortium of CNRS, CELIA, and Thales supported by the French public investment bank.

New challenges in Laser-Plasma Interaction research for Inertial Fusion Energy

• G. Cristoforetti
• L.A. Gizzi

Inertial Fusion Energy (IFE) relies on repetitive and energy-efficient compression, ignition, and burn of a millimeter-sized spherical pellet containing the fuel. In the original Direct-Drive (DD) scheme of Inertial Confinement Fusion (ICF), the laser beams impinge directly on the pellet and drive the implosion, delivering their energy to the plasma at densities below the critical density. In the Indirect-Drive (ID) scheme, laser beams impinge on the inner walls of the Hohlraum surrounding the pellet, generating X-rays that drive the implosion. In both schemes, inelastic scattering of the laser light with density fluctuations can drive the excitation of electron or ion-acoustic plasma waves, resulting in the growth of the so-called laser-plasma instabilities (LPI), which can have a dramatic impact on the implosion performance and therefore are a great concern for ICF. Among laser-plasma instabilities, Stimulated Brillouin Scattering (SBS) and Stimulated Raman Scattering (SRS) lead to a net loss of laser energy and, therefore in the increase of the driver energy requirements. Cross-Beam Energy Transfer (CBET) can produce an imbalance of the laser beam coupling and, thus, compromise the compression efficiency. Finally, SRS and Two Plasmon Decay (TPD) can result in the generation of hot electrons that can be absorbed by the cold fuel, enhancing its entropy and preventing ignition. In the past 40 years, significant effort was dedicated to the theoretical and experimental investigation of these processes and identifying the proper ways to control or mitigate their effects on the implosion performance, finally leading to the recent successful ignition demonstration at the National Ignition Facility using the ID scheme. New investigations are, however, needed for interaction conditions typical of the DD scheme, which is more suitable for energy production and a future reactor. Even more important is the investigation of LPI in advanced ignition schemes like the Shock Ignition scheme, where the laser intensity is higher than in the classical DD scheme. In the first part of the talk, we will give an overview of the LPI mechanisms, highlighting their role in the different ICF and advanced ignition schemes. We will discuss the new challenges for LPI investigation, as well as the recent technology advancements under investigation for mitigating LPI effects. In the second part, we will summarize recent experimental results on LPI studies obtained in campaigns at Gekko XII, PALS, VULCAN, and ELI laser facilities, carried out in the framework of the EUROfusion research program, aimed at understanding the role of plasma and laser parameters on the growth of SRS and TPD and at identifying the mechanisms originating hot electrons in conditions relevant for the Shock Ignition scheme.