Description
Inertial Fusion Energy (IFE) is increasingly regarded as a credible long-term option for large-scale, carbon-free power production. The recent demonstration of ignition with net target gain at the National Ignition Facility (NIF) marks a decisive scientific milestone for laser-driven inertial confinement fusion (ICF). Since 2022, repeated ignition shots have been achieved, with fusion gains increasing from ~1.5 [1] to above ~4 by 2025. These results validate decades of theoretical and experimental efforts devoted to implosion symmetry control, instability mitigation, and ignition physics.
Yet single-shot ignition at gain of a few is not equivalent to a viable energy pathway. An economically relevant fusion system delivering >750 MW of electricity would ultimately require repetition rates of the order of 10 Hz and target gains exceeding 100. Although advances in laser efficiency, target production and injection, and reactor technologies are indispensable, the achievable fusion gain remains fundamentally conditioned by the underlying ignition physics. In this respect, the central question is not merely how to scale present approaches, but whether alternative ignition regimes offer intrinsically more favorable gain margins and robustness.
This talk will therefore focus on a comparative assessment of advanced ignition concepts aimed at substantially increasing target gain beyond conventional central hot-spot ignition. Concepts proposed over the past three decades – including shock [2] and shock-augmented ignition [3], electron- [4] and proton-driven fast ignition [5], and magnetized inertial confinement fusion [6] – will be evaluated in terms of physical robustness, scalability toward high gain (>100), sensitivity to asymmetries and instabilities, and compatibility with existing or emerging large-scale laser infrastructures.
Drawing on 25 years of research and teaching experience and a synthesis of key reference works, I will propose an independent perspective on the most promising physics-driven strategies for substantially increasing fusion gain within the current international academic and emerging semi-industrial ecosystem. Particular emphasis will be placed on identifying the critical physical bottlenecks that may ultimately determine which approaches can realistically mature in the coming decades.
References
[1] H. Abu-Shawareb et al., Phys. Rev. Lett. 132, 065102 (2024).
[2] R. Betti et al., Phys. Rev. Lett. 98, 155001 (2007).
[3] R.H.H. Scott et al., Phys. Rev. Lett. 129, 195001 (2022).
[4] M. Tabak et al., Phys. Plasmas 1 (5), 1626 (1994).
[5] M. Roth et al., Phys. Rev. Lett. 86, 3, 436-439 (2001).
[6] L. J. Perkins et al., Phys. Plasmas 24, 062708 (2017).