通過徑向輸運的能量PT-PR將沉積到限制器上

1、SOL and Limiter Configurationin HT-7(for discussion)Wan BaonianFor the HT-7 TeamOutline What is SOL? Elementary properties of SOL How does SOL affect RF coupling Suggestion for modification of the HT-7 limiter ConclusionWhat is SOL? SOL-Scrap of Layer Connection length2LC: the distance along a B-lin

2、e in the SOL measured from one point of contact with a limiter to the nextSingle T-limiter: LCRqSingle P-limiter: LCR Properties of SOL & sheathThe total cross-field particle (energy) flux is balanced by the flux reaching to the limiter: n=(2DLC/cs)1/2Typically Bohm diffusion at the edg: Dbohm=0

3、.6Te/BCross-field particle flux: SpnD/ n2Sheath at the limiter surface: Vsf 3TeThe limiter material affects the SOL through: secondary electron emission and ion backscatter distribution Properties of SOL & limiter 通過徑向輸運的能量PT-PR將沉積到限制器上，但直接沉積到與等離子體相切的限制器面上的能量很小。絕大部分能量將進(jìn)入SOL后經(jīng)平行輸運到達(dá)限制器側(cè)表面。 環(huán)向限制器與

4、等離子體不相切的面積充當(dāng)了SOL區(qū)域，分散了熱流密度。面積2Rw or 2R/sin。 對極向限制器而言，熱流密度集中在環(huán)向的兩側(cè)，面積 4.1 1017/m3, the optimised density is about 4 times the cut-off density which is 1.6x1018/m3.For IBW, the mode transformation near ffpi=0.21(ni/A)1/2 Hz; at 30MHz, ni4.1 1016/m3, at 27MHz, ni3.3 1016/m3.When the density at the IBW

5、antenna is lower, MT of EPW to IBW is sensitive to the density gradient scale length, hence to ponderomotive effects & parametric instabilities. There is a mode called the cold electrostatic ion cyclotron wave (CESICW) between H and ii (24-26.3MHz at 2T & H/(H+D)20-30%). It is possible to co

6、uple directly to CESICW and then transform to IBW.Heat load on the antenna, another big issue.Modification of the HT-7 limiter Very small between tile gap, hence enhanced local particle & heat sink, might cause strong local recycling. Complicated SOL properties, hence nonuniform density at the antenna. High capability of heat exhaust.Modification of the HT-7 limiter Significantly extend Lc Rq/2 hence larger & more uniform Relative simple SOL properties, hence uniform density at the antenna. Improved heat load density at end of the limiter. Reduced limiter surfa