电子迥旋加热等离子体及热电子环特性的实验研究

在简单磁镜MM-2中,采用15GHZ大功率迴旋管进行了电子迴旋共振加热(ECRH)实验。结果表明,随充气压强的提高,预电离时间迅速变短。在高气压“C-模式”运行区,等离子体径向密度分布呈马鞍形。在迴旋管输出30kW功率的条件下,适于建立热电子环的气体压力窗为(0.4—1.2)×10^-5Torr。利用一个可移动Laugmuir探针配合反磁测量的简便方法,在中心场为2.95kG时,确定了电子环半径为7cm,环厚约4cm,环的轴向边界由z=±10cm一直延伸到z=±20cm。热电子温度为140—170keV,热电环平均β值为(4—5)％。观测到了由热电子环不稳定性引起的迸发式径向电子逃逸,并同时发生反磁信号跌落。

EXPERIMENTAL INVESTIGATION ON PROPERTIES OF E. C. H. PLASMA AND HOT ELECTRON RING

The ECRH experiment has been carried out on a simple mirror-MM-2 device by use of a 15 GHz high power gyrotron. The experimental results showed that the preionization time will be rapidly shorten following raising the pressure of puffed gas. Duing the "C-mode" operation where the gas pressure is higher, the radial profile of plasma density exhibits a saddle shape. The gas "pressure window" for building a hot electron ring is (0.4-1.2)×10^-5 Torr, as the gyrotron output is about 30 kW. Simply by using a movable Langmuire probe accompanied with diamagnetic measurment. it has been determined that the hot electron ring radius is 7 cm, the thickness is about 4 cm and the axial boundary of the ring extends from Z= ±10 cm to Z=±20cm, when the central field is 2.95kg. The hot electron temperature is 140 to 170 keV. The average beta value of hot electron ring is (4-5)%. The radial bursts of electrons due to ring instabilities accompanied with the drops of the diamagnetic signal have also been observed.