Abstract

The Fusion Nuclear Science Facility (FNSF) is a proposed tokamak reactor with the mission to investigate operation of a fusion reactor in a nuclear environment. The high neutron fluence component of the FNSF mission requires steady-state operation for extremely long pulses ($t_{pulse}\sim$months) at full power. Plasma sustainment and current drive will be critical components of a successful FNSF. COMSOL Multiphysics® software is used for combined radiofrequency (RF) and thermal simulations of the lower hybrid current drive antenna system. These simulations consider the resistive RF losses in the antenna including realistic surface roughness and a range of potential materials. The thermal analysis adds volumetric nuclear heating, plasma heat flux on leading edges, and electromagnetic radiation from the plasma to the RF heating calculated by COMSOL. Additional neutronics calculations have been performed to determine the impact of these antenna designs on activated waste disposal for the materials considered. The simulations show that it is technically feasible to implement a fully active multijunction (FAM) rather than a passive-active multijunction (PAM) style of antenna if the septum between adjacent waveguides is sufficiently wide and the thermal conductivity of the structural material is sufficiently high. The FAM has the benefit of higher achievable power density with respect to the PAM, which results in a more compact antenna with potentially lower impact on neutron shielding and tritium breeding. These considerations point to tungsten rather than steel as the preferred structural material in constructing the antenna.

抽象的

聚变核科学设施（FNSF）是拟议的托卡马克反应堆，其任务是研究核反应堆在核环境中的运行。FNSF任务的高中子注量部分需要稳态操作才能产生极长的脉冲（${Ť}_{pü升sË}〜$个月）。等离子体维持和电流驱动将是成功的FNSF的关键组成部分。COMSOLMultiphysics®软件用于下部混合电流驱动天线系统的组合射频（RF）和热仿真。这些模拟考虑了天线中的电阻性RF损耗，包括实际的表面粗糙度和一系列潜在的材料。热分析增加了体积核加热，前沿的等离子体热通量以及从等离子体到COMSOL计算的RF加热的电磁辐射。已经进行了其他中子学计算，以确定这些天线设计对所考虑材料的活性废物处置的影响。仿真表明，如果相邻波导之间的间隔足够宽且结构材料的导热率足够高，则实现完全有源多结（FAM）而不是无源-有源多结（PAM）样式在技术上是可行的。与PAM相比，FAM具有更高的可实现功率密度的优势，这使得天线更加紧凑，对中子屏蔽和t的繁殖的影响可能更低。这些考虑表明，在构造天线时，钨而不是钢是优选的结构材料。与PAM相比，FAM具有更高的可实现功率密度的优势，这使得天线更加紧凑，对中子屏蔽和t的繁殖的影响可能更低。这些考虑表明，在构造天线时，钨而不是钢是优选的结构材料。与PAM相比，FAM具有更高的可实现功率密度的优势，这使得天线更加紧凑，对中子屏蔽和t的繁殖的影响可能更低。这些考虑表明，在构造天线时，钨而不是钢是优选的结构材料。