The MHD equilibrium properties of neutral beam heated plasmas have been experimentally investigated in the Compact Helical System (CHS)-a low aspect ratio (Ap ~ 5) heliotron/torsatron. This configuration is characterized by a strong breaking of helical symmetry. The radial profiles measured by various diagnostics have shown a significant Shafranov shift due to the plasma pressure. The deviation of the magnetic axis from is vacuum position has become as large as 50% of the minor radius. When the three-dimensional equilibrium code VMEC is used to reconstruct the equilibrium from the experimental data, the result is in good agreement with the experimentally observed Shafranov shift as well as with the diamagnetic pressure in plasmas with ⟨β⟩ ⩽ 1.2% and β0 ⩽ 3.3%. This beta values corresponds to half of the conventional equilibrium β limit defined by the Shafranov shift reaching a value of half of the minor radius. Although tangential neutral beam injection causes pressure anisotropies, p||/p⊥ ⩽ 3, the description of the equilibrium assuming isotropic pressure is consistent with the experiment
中性束加热等离子体的磁流体力学平衡特性已在紧凑螺旋系统（CHS）——一种低环径比（Ap ~ 5）的螺旋器/托萨特龙装置——中进行了实验研究。该构型以螺旋对称性的显著破缺为特征。通过多种诊断手段测量的径向分布显示，由于等离子体压力引起的Shafranov位移显著。磁轴偏离真空位置的程度已达到小半径的50%。当使用三维平衡代码VMEC根据实验数据重建平衡时，结果与实验观测到的Shafranov位移以及抗磁压力在⟨β⟩ ≤ 1.2%和β0 ≤ 3.3%的等离子体中均吻合良好。该β值对应于常规平衡β极限的一半，该极限由Shafranov位移达到小半径一半的值来定义。尽管切向中性束注入引起了压力各向异性，p||/p⊥ ≤ 3，但假设各向同性压力的平衡描述与实验一致。