Study on formation mechanism of dust particles in divertor plasma simulators

在NAGDIS-II线性偏滤器等离子体模拟器上研究了高密度氢等离子体和混合氢/氦等离子体辐照石墨表面碳尘粒子的形成。碳尘颗粒产生在石墨表面的中心区域，面对高密度等离子体。在外围区域中没有灰尘颗粒形成。这些观察结果表明，由于等离子体柱中心的强等离子体流导致的碳氢离子的再沉积过程是决定粉尘生长以及化学溅射的关键因素之一。低能量和高通量等离子体暴露在钨表面导致气泡/孔洞的形成。随后的He等离子体暴露在2,000 K的气泡丰富的表面上形成一个孔结构的表面上，包括泡表面，和一些水泡崩溃，由于再结晶和气泡形成的水泡皮肤上。在W表面上，由于在1，600 K下预暴露He而形成了孔结构，在550 K下暴露于氘等离子体后观察到颗粒喷射。

Formation of carbon dust particles on a graphite surface irradiated by a high-density hydrogen plasma and a mixed hydrogen/helium plasma has been investigated in the NAGDIS-II linear divertor plasma simulator. Carbon dust particles are generated at the center region of the graphite surface facing the high-density plasma. No dust particles are formed in the peripheral region. These observations indicate that the re-deposition process of the hydrocarbon ions due to a strong plasma flow at the center of the plasma column is one of the key factors determining the dust growth as well as chemical sputtering.Low-energy and high-flux plasma exposures on tungsten surfaces result in blister/hole formation. Subsequent He plasma exposure at 2,000 K on the blister-rich surface forms a hole structure on the surface, including the blister surface, and some blisters collapse due to recrystallization and bubble formation on the blister skin. Grain ejections were observed after deuterium plasma exposure at 550 K on a W surface on which a hole structure had formed due to He pre-exposure at 1,600 K.