For the interpretation of the line radiation observed from laser induced ablation spectroscopy (LIAS) such parameters as the density and temperature of electrons within very compact clouds of atoms and singly charged ions of ablated material have to be known. Compared to the local plasma conditions prior to the laser pulse, these can be strongly changed during LIAS since new electrons are generated by the ionisation of particles ejected from the irradiated target. Because of their transience and spatial inhomogeneity it is technically difficult to measure disturbances induced in the plasma by LIAS. To overcome this uncertainty a numerical model has been elaborated, providing a self-consistent description for the spreading of ablated particles and accompanying modifications in the plasma. The results of calculations for LIAS performed on carbon-containing targets in Ohmic and additionally heated discharges in the tokamak TEXTOR are presented. Due to the increase in the electron density the 'ionisation per photon' ratio, S/XB factor, is significantly enhanced compared to unperturbed plasma conditions. The impact of the amount of material ablated and of the plasma conditions before LIAS on the level of the S/XB-enhancement is investigated.
为了解释激光诱导烧蚀光谱（LIAS）所观测到的线辐射，需要知道烧蚀材料形成的非常致密的原子和单电荷离子云中的电子密度和温度等参数。与激光脉冲之前的局部等离子体条件相比，这些参数在LIAS期间可能发生显著变化，因为烧蚀靶材喷射出的粒子电离会产生新的电子。由于这些扰动具有瞬态性和空间不均匀性，因此技术上难以测量LIAS在等离子体中引起的扰动。为克服这一不确定性，我们建立了一个数值模型，该模型能够自洽地描述烧蚀粒子的扩散及其对等离子体产生的伴随修改。本文给出了在托卡马克TEXTOR中，对碳靶在欧姆放电和附加加热放电条件下进行LIAS的计算结果。由于电子密度的增加，与未扰动的等离子体条件相比，“电离光子比”S/XB因子显著增强。本文还研究了烧蚀材料量以及LIAS之前的等离子体条件对S/XB增强程度的影响。