Isotope corrections of ablation rates in fusion plasma for different solid hydrogen molecule pellets

Abstract

Abstract:

The isotope corrections of ablation rates in fusion plasma forfive combinations of solid isotopic hydrogenic pellets, H₂, HD, D₂, DT, T₂have been studied. The results show that modifications caused by the isotope effect for pellet erosion speeds range form 1 for hydrogen pellet down to 0.487 for tritium pellet and are not negligible in ablation rate calculations. These effects lead to deeper pellet substance deposition and improve the core fueling efficiency. The ITER core fueling difficulty will be moderately alleviated by taking into account of the isotope effects. For instance, our other numerical calculation results show that, with DT pellet of radius r_p0= 0.5cm injected from lower field side to get the penetration length L= 200cm in the ITER plasma, the required pellet speed will be reduced to 16.2km•s^-1from 24.27km•s^-1based on Kuteev 2D lentil model, and to 5.4km•s^-1from 8.07km•s^-1based on the Parks model. Our other work also shows if a DT pellet with size r_p0=0.5cm is injected from mid-plane high field side of ITER, the ablated substance of pellet can be deposited to the core plasma even if the velocity is as lowas 173m•s^-1by considering the isotope effects and the drift in major radius direction caused by the vertical polarization current due to the difference of specific pressures between the inner and outer cloudlet.

Key words: Isotope effects, Corrections of ablation rates;High field side injection, ITER

摘要：

对五种不同组合的固态氢同位素靶丸H₂、HD、D₂、DT和T₂在聚变等离子体中的消融率作了同位素修正。结果表明,由

于这种新机制───同位素效应,引起的靶丸半径烧蚀率修正从氢靶丸的1下降到氚靶丸的 0.487。因而在消融率计算时

是不可忽略的,这些修正可导致更深的靶丸消融物质沉积因而改善芯部加料效率。更重要的是,

考虑到同位素效应后,对ITER的加料困难有适度的减轻。进一步的数值计算工作表明,以低场侧

注入半径r_p0=0.5cm的DT靶丸,同样渗入ITER等离子体100cm,按Kuteev的2D透镜模型,同位素

修正使要求靶丸的初速度从v_p0=24.27×10⁵cm•s^-1减小16.2×10⁵cm•s^-1,而对Parks模型,从v_p0=

8.07×10⁵cm•s^-1减小到5.4×10⁵cm•s^-1。如果从中平面高场侧注入尺寸r_p0= 0.5cm的DT靶丸,当

合并考虑同位素修正和由于消融云内外比压差产生的净垂直极化电流引起的沿大半径方向漂

移后,v_p0可降低到工程技术上比较容易实现的低速 1.73×10⁴cm•s^-1从而可能使靶丸的消融物

质沉积到ITER等离子体中心。

关键词: 同位素效应, 消融率修正, 高场侧注入, ITER

CLC Number:

TL62+4

Deng Bai-quan,Peng Li-ling,Yan Jian-cheng,Wang Xiao-yu. Isotope corrections of ablation rates in fusion plasma for different solid hydrogen molecule pellets[J]. NUCLEAR FUSION AND PLASMA PHYSICS, 2005, 25(1): 49-54.

邓柏权,彭利林,严建成,王晓宇. 改善芯部加料效率的新机制研究[J]. 核聚变与等离子体物理, 2005, 25(1): 49-54.

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