In the heart of nuclear fusion research, a recent study led by P. Vincenzi of Consorzio RFX and the Institute for Plasma Science and Technology in Italy has shed new light on the operational constraints of the Neutral Beam Injection (NBI) system in the International Thermonuclear Experimental Reactor (ITER). The findings, published in the journal ‘Nuclear Fusion’, focus on a critical issue known as shine-through (ST) losses, which could significantly impact the longevity of ITER’s plasma-facing components (PFCs).
Shine-through occurs when a portion of the injected neutral beam remains un-ionized and directly strikes the PFCs, potentially causing severe damage. This phenomenon imposes stringent limits on the operational window of the NBI system, which is pivotal for heating and current drive in ITER’s plasma. The study delves into the complex interplay between plasma density, beam energy, and injection geometry, using advanced numerical simulations to map out these dependencies across various plasma scenarios, particularly for the upcoming DT-1 phase, which will see the first NBI operations.
Vincenzi explains, “Understanding and mitigating shine-through losses is crucial for the efficient operation of the NBI system. Our research provides a new heuristic formula that allows for the calculation of the ST fraction and the minimum plasma density required for NBI operations. This is a significant step forward in ensuring that the beam power can be fully utilized without compromising the operational lifetime of ITER’s components.”
The study also refines previous estimates of the maximum acceptable ST power on PFCs, informed by recent changes in the ITER blanket design. This refinement is particularly relevant given the evolving design and operational parameters of ITER. By establishing clear operational limits for both Hydrogen and Deuterium NBI in different plasma compositions, the research offers a roadmap for future plasma operation plans.
Moreover, the study compares commonly used beam ionisation codes, evaluating their reliability within the investigated parameter space. This comparison is essential for validating simulation tools and ensuring their accuracy in predicting ST losses. “The reliability of these codes is paramount for the success of ITER’s experimental phases,” Vincenzi notes. “Our findings not only inform current operations but also guide the development of future simulation tools.”
The implications of this research extend beyond ITER. As the energy sector increasingly looks towards fusion as a potential source of clean, abundant power, understanding and mitigating ST losses will be crucial for the design and operation of future fusion reactors. The study’s findings could influence the development of more efficient and durable PFCs, as well as the optimization of NBI systems in commercial fusion reactors.
By providing a comprehensive analysis of ST losses and their impact on NBI operations, Vincenzi’s work contributes to the broader goal of making fusion energy a viable and sustainable part of the global energy mix. As ITER moves closer to its experimental phases, this research will be instrumental in shaping the future of fusion energy, ensuring that the promise of clean, limitless power becomes a reality. The study, published in ‘Nuclear Fusion’, represents a significant advancement in the field, offering valuable insights that will guide the development of future fusion technologies.
