Microscale turbulence drives not only particle and heat transport but also energy exchange between different particle species. Previous local gyrokinetic studies have shown that turbulent energy exchange can exceed collisional exchange in weakly collisional plasmas, and that ion temperature gradient (ITG) turbulence may hinder ion heating by alpha-heated electrons. In addition, it has been clarified that trapped electron mode (TEM) turbulence transfers energy from electrons to ions, thereby enhancing ion heating. In this work, we extend these studies by examining the impact of turbulent energy exchange on the global temperature profiles at a steady state using the one-dimensional transport solver GOTRESS. For the case of DIII-D discharge #128913, turbulent energy exchange has minimal influence on temperature profiles. However, in the case of enhanced electron heating in a DIII-D-like tokamak plasma, energy transfer from hot electrons to cold ions driven by TEM turbulence becomes comparable to, or even exceeds, the collisional contribution, leading to a significant increase in the ion temperature profile. For ITER Baseline and SPARC standard H-mode scenarios, the turbulent energy exchange is largely compensated by the collisional one, producing only small effects. These results indicate that the impact of turbulent energy exchange on the global temperature profiles in steady‐state conditions of future fusion reactor scenarios is expected to be negligibly small, although it can become significant in situations such as plasma start-up phases, where the heating power is strongly unbalanced between electrons and ions.

Ionization waves exhibiting chaotic oscillations were periodized by modulating the discharge voltage. The oscillations were made periodic by applying modulation to the discharge voltage using a square wave. Furthermore, the dynamic behavior when the duty cycle of the square wave was varied was investigated. The behavior of the transition threshold separating the chaotic and periodic states was investigated. A difference was confirmed between the modulation value causing the transition from the chaotic state to the periodic state when the amplitude of the modulation voltage (square wave) was increased, and the modulation value causing the transition from the periodic to the chaotic state when the amplitude was decreased. The degree of periodization of the orbit was quantitatively evaluated using the largest Lyapunov exponent and the CH diagram, which confirmed the transition from the chaotic to the periodic state. Furthermore, chaotic periodization was possible with a duty cycle close to 50%.

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.

This article presents the first experimental results from a novel configuration in Heliotron J, which features a shallow magnetic well in the core of the plasma. A broadband coherent fluctuation of approximately 10 kHz is observed in a low-β electron cyclotron heated (ECH) plasma at rotational transform ι/2π = 0.55 in this configuration, while no mode appears in a deep magnetic well configuration. An electron cyclotron emission measurement shows the mode is excited in the core region where the magnetic well is shallow. This indicates Heliotron J is able to sustain viable plasmas with an edge-hill, although these can be destabilised even at low density and pressure.