Determination of electron densities by diode-laser absorption spectroscopy in a pulsed ICP
Determination of electron densities by diode-laser absorption spectroscopy in a pulsed ICP
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DOI：
10.1088/0963-0252/20/1/015022
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发表时间：
2011-02-01
影响因子：
3.8
通讯作者：
Czarnetzki, U.
中科院分区：
文献类型：
--
作者：
Celik, Y.;Aramaki, M.;Czarnetzki, U.
提出了一种通过氩亚稳态吸收光谱测定低压 (1 Pa) 脉冲 ICP 放电中电子密度的新方法。通过使用调谐在 696.73 nm 真空波长的外腔二极管激光器，记录了余辉中 Ar1s(5) 态亚稳态氩原子吸收的时间行为。分析模型激发了在我们的实验条件下均匀亚稳态密度分布的假设。此外，还开发了亚稳态密度衰减的详细模型，包括空间电子密度分布及其时间衰减。这允许根据测量的数据确定电子密度。通过该技术获得的密度与朗缪尔探针测量获得的密度之间的比较显示出极好的一致性。此外，通过比较数据和模型，确定了余辉中的电子密度衰减时间、双极扩散常数和有效电子温度。电子衰变时间与密度的比例表明复合。所获得的低电子温度大大减少了扩散，并且预计会导致复合率增加。
A novel method to determine electron densities in a low pressure (1 Pa) pulsed ICP discharge via absorption spectroscopy on argon metastables is presented. By use of an external cavity diode laser tuned at a vacuum wavelength of 696.73 nm the time behaviour of the absorption from metastable argon atoms in the Ar1s(5) state in the afterglow is recorded. An analytical model motivates the assumption of a homogeneous metastable density distribution under our experimental conditions. Further, a detailed model for the metastable density decay is developed, including the spatial electron density distribution and its temporal decay. This allows determination of the electron density from the measured data. Comparison between densities obtained by this technique and by Langmuir probe measurements shows excellent agreement. Furthermore, the electron density decay time, the ambipolar diffusion constant and the effective electron temperature in the afterglow are determined comparing data and model. The scaling of the electron decay time with density indicates recombination. The obtained low electron temperature reduces diffusion very much and can be expected to cause an increased recombination rate.