Ideal MHD stability and characteristics of edge localized modes on CFETR

Abstract

Investigation on the equilibrium operation regime, its ideal magnetohydrodynamics (MHD) stability and edge localized modes (ELM) characteristics is performed for the China Fusion Engineering Test Reactor (CFETR). The CFETR operation regime study starts with a baseline scenario (R = 5.7 m, B T = 5 T) derived from multi-code integrated modeling, with key parameters β N , β T , β p varied to build a systematic database. These parameters, under profile and pedestal constraints, provide the foundation for the engineering design. The long wavelength low-n global ideal MHD stability of the CFETR baseline scenario, including the wall stabilization effect, is evaluated by GATO. It is found that the low-n core modes are stable with a wall at r/a = 1.2. An investigation of intermediate wavelength ideal MHD modes (peeling ballooning modes) is also carried out by multi-code benchmarking, including GATO, ELITE, BOUT++ and NIMROD. A good agreement is achieved in predicting edge-localized instabilities. Nonlinear behavior of ELMs for the baseline scenario is simulated using BOUT++. A mix of grassy and type I ELMs is identified. When the size and magnetic field of CFETR are increased (R = 6.6 m, B T = 6 T), collisionality correspondingly increases and the instability is expected to shift to grassy ELMs.

Achieving a robust grassy-ELM operation regime in CFETR

“…Since ballooning mode width is narrower, it might be more likely for a high-n ballooning mode at the pedestal top, where diamagnetic stabilization is weakest, to become unstable first. This has been reported in a previous study [19] and the most unstable mode spectrum in our case ( Fig.7(a)) also supports that.…”

“…9(c)], which further destabilizes other neighboring modes. Second, the down cascade from high n to lower n modes is a common feature observed in other simulations [19] . The dominant n=5 mode in the nonlinear phase could be driven by a combination of the pedestal pressure and current.…”

“…= 33, where y is the parallel coordinate and z is the toroidal angle. Similar to Ref 19,. the radial boundary condition is set as ̃= 0, ∇ ⊥ Note that we have to adjust the inner boundary condition by increasing the perturbed pressure gradient to balance the convective term 〈̃〉 • ∇ 0 in Eq.…”

Discrete Alfvén eigenmodes excited by energetic particles in China Fusion Engineering Test Reactor

“…其运行将分为两 个阶段: 第一阶段实现200 MW的聚变功率和氚自持 的稳态运行(装置的大半径R = 5.7 m, 小半径a=1.6 m, 中心磁场B T =5.0 T); 第二阶段实现1000 MW的聚变功 率并示范聚变电能输出 [25][26][27] . 为了在CFETR上演示氚 自持的稳态运行以及聚变电能输出, 提出了两种稳态 运行模式, 分别为基准(Baseline)和先进(Advanced)稳 态运行模式 [28][29][30] , 后者将获得比前者更高的聚变功率, 有望达到CFETR最终的科学目标. 此外, CFETR装置 的相关不稳定性的预研是其投入建设的重要基础, 为 了通过先进运行模式实现其最终的目标, 首先基于装 置的基准运行模式预研阿尔芬本征模的相关不稳定 性, 并且在该装置上已有TAE, RSAE及BAE的相关理 论研究工作 [31,32] .…”

Destabilizing effects of edge infernal components on n = 1 resistive wall modes in CFETR 1GW steady-state operating scenario

“…The China Fusion Engineering Test Reactor (CFETR) project aims to bridge the gap between the experimental fusion reactor ITER [4] and the future fusion power plant DEMO [5]. During the past few years, significant progress has been made in the CFETR conceptual physics and engineering design [6][7][8][9][10][11][12][13][14][15][16][17][18]. Since 2018, a new design scenario of CFETR has been adopted with major radius R 0 = 7.2m and minor radius a = 2.2m, primarily targeting the long-pause self-sustainable burning plasmas with fusion power production up to 1GW in the steady-state operation (SSO) [19].…”