An attractive high-density operational regime which is a so-called internal diffusion barrier (IDB) has been discovered in a helical divertor configuration on the Large Helical Device (LHD). The IDB is characterized by steep density gradients and the plasma profile is divided by the IDB into a high-density core plasma and a low density mantle plasma. The IDB enables the core plasma to access the high-density/high-pressure regime. The attainable central density exceeds 1 × 1021 m−3 and the central pressure reaches ≈1.5 times atmospheric pressure. Core pellet fuelling is absolutely essential for the IDB formation and it is reproducibly obtained by employing intensive multiple-pellet injection. In the IDB core plasma, the particle diffusion coefficient is kept at a considerably low level, 0.05 m2 s−1, in spite of high-density and steep-density gradients whereas an inward particle convection velocity is not observed.
大型螺旋装置（LHD）的螺旋偏滤器结构中，发现了一种具有吸引力的高密度运行状态，即所谓的内部扩散垒（IDB）。IDB的特征在于陡峭的密度梯度，等离子体剖面被IDB划分为高密度芯部等离子体和低密度边缘等离子体。IDB使芯部等离子体能够进入高密度、高压状态。可达到的芯部密度超过1×10²¹ m⁻³，中心压力约为大气压的1.5倍。芯部燃料注入对于IDB的形成至关重要，通过多次强化的燃料注入可稳定地获得该状态。在IDB芯部等离子体中，尽管存在高密度和陡峭的密度梯度，粒子扩散系数仍保持在相当低的水平，约为0.05 m² s⁻¹，且未观察到内向粒子对流速度。