Plasma and Fusion Research

Volume 21, 1404018 (2026)

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Isentropic Scaling Law for Implosions of Solid Spherical Targets

Takashi SHIROTO

: Department of Physics, Nagoya University, Nagoya 464-8602, Japan

(Received 16 November 2025 / Accepted 5 January 2026 / Published 25 March 2026)

Abstract

In this study, an isentropic scaling law is developed for direct-drive implosions of solid spherical targets—a setup frequently employed in Fast Ignition Realization Experiments—in order to estimate densities at maximum compression. Adiabatic theories usually cannot explain shock-driven compression due to entropy production; however, differences among similar implosion scenarios can be approximated by isentropic laws. Numerous one-dimensional implosion simulations support for the proposed isentropic scaling law, especially regarding the relationship between confinement time and density at maximum compression.

Keywords

implosion, hydrodynamics, fast ignition, theoretical model

DOI: 10.1585/pfr.21.1404018

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