Sheath potential coefficient α is a key parameter, which is used to estimate plasma potential () for edge plasma physics study. Recently, a series of experiments has been carried out under hydrogen plasmas in the J-TEXT tokamak with swept probe, which is employed for current–voltage (I–V) characteristic measurement. Electron temperature is evaluated from I–V curve by three-parameter fitting method, and the electron energy probability function shows that electron distribution is Maxwellian both outside and inside of last closed flux surface (LCFS). Plasma potential is obtained by crossing point between I–V exponential fitting curve and electron saturation current extrapolating line, which is in good agreement with first derivative probe technique. The α coefficient profile in the vicinity of the LCFS is obtained, which is in the range of 2.1–3, and decreases from outside to inside of LCFS.

鞘层电势系数α是关键参数，用于估算边缘等离子物理研究的等离子体电势（）。最近，一系列的实验已经在氢气等离子体中与扫探针，其被用于电流-电压（J-TEXT托卡马克进行我- V特性测定）。电子温度从评价我- V由三参数拟合方法的曲线，和电子能量概率函数显示，电子分布是麦克斯韦外部和最后封闭的通量面（LCFS）的内部。血浆电势通过I – V之间的交叉点获得指数拟合曲线和电子饱和电流外推线，与一阶导数探针技术吻合良好。得到的LCFS附近的α系数分布在2.1–3范围内，并且从LCFS的外部到内部逐渐减小。