Characterization of an inductively coupled N2 plasma using sensitive diode laser spectroscopy
Characterization of an inductively coupled N2 plasma using sensitive diode laser spectroscopy
复制标题
使用灵敏二极管激光光谱表征电感耦合 N2 等离子体
DOI：
10.1088/0022-3727/37/15/004
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
L. Thornton
中科院分区：
文献类型：
--
作者：
B. Bakowski;G. Hancock;R. Peverall;G. Ritchie;L. Thornton
本文对电感耦合等离子体中产生的N2态进行了光学研究。使用离子通量测量和宽带光发射来表征放电的运行，并且随着施加功率的增加，观察到从电容耦合到电感耦合的明显变化。在100w和10mtorr下的典型离子通量为1.8 × 1018 m2 s - 1，由此推断出离子密度为~1.5 × 109 cm - 3。采用二极管激光腔增强吸收光谱（CEAS）在686 nm波段探测其状态。P33带头光谱用于测定分子在v = 0水平下的平移（Ttr）和旋转（Trot）温度。发现它们处于平衡状态，但依赖于等离子体参数；在10mtorr放电中，Trot≈Ttr，变化范围从5w时的~ 300k到400w时的~ 450k。利用腔衰荡时间测量镜面反射率，通过校准CEAS技术确定了各个自旋-旋转状态下的绝对数量密度。在100 W射频功率和10 mTorr压力的典型条件下，发现v = 0水平下的总体种群为（1.19±0.07）× 1010 cm−3，对应于产生该水平的放电效率为~10−5。提出了一种动力学方案来解释在v = 0水平上A态浓度的压力和功率依赖性。
In this paper, we present an optical study of the state of N2 produced in an inductively coupled plasma. The operation of the discharge was characterized using ion flux measurements and broadband optical emission, and a clear change from capacitively to inductively coupled behaviour was observed with increasing applied power. The typical ion flux at 100 W and 10 mTorr was found to be 1.8 × 1018 m2 s−1, from which a ion density of ~1.5 × 109 cm−3 was inferred. Diode laser cavity enhanced absorption spectroscopy (CEAS) was used to probe the state via the band at 686 nm. P33 band head spectra were used to determine both the translational (Ttr) and rotational (Trot) temperatures of the molecules at the v = 0 level. These were found to be in equilibrium but dependent on plasma parameters; in a 10 mTorr discharge, Trot ≈ Ttr, varying from ~300 K at 5 W to ~450 K at 400 W applied power. Absolute number densities in individual spin–rotation states were determined by calibrating the CEAS technique using the cavity ringdown time to measure the mirror reflectivity. The overall population in the v = 0 level was found to be (1.19 ± 0.07) × 1010 cm−3 under typical conditions of 100 W radio frequency power and 10 mTorr pressure, corresponding to a discharge efficiency for the production of this level of ~10−5. A kinetic scheme is presented to account for the pressure and power dependence of the A-state concentration in the v = 0 level.