Cavity ringdown studies of the E-H transition in an inductively coupled oxygen plasma: comparison of spectroscopic measurements and modelling
Cavity ringdown studies of the E-H transition in an inductively coupled oxygen plasma: comparison of spectroscopic measurements and modelling
复制标题
电感耦合氧等离子体中 E-H 转变的腔衰荡研究：光谱测量和建模的比较
DOI：
10.1088/1361-6595/ac9d62
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发表时间：
2022
影响因子：
3.8
通讯作者：
Rogers S
中科院分区：
文献类型：
--
作者：
Rogers S
基态氧原子，O（3 P），在100毫托的氧等离子体中存在的绝对数密度已被确定为使用腔衰荡光谱（CRDS）的工作功率的函数。解离分数增加了一个数量级，从50 W时的0.8%到250 W时的8%，并反映了在此功率范围内电子密度的类似增加。发射光谱表明，E-H跃迁伴随着O2转动加热的增加，这种行为在通过拟合多普勒限制的O（3 P）CRDS数据确定的平移温度中也观察到.测量通过体积平均动力学模型进行情境化，该模型使用测量的O（3 P）和O 2（a 1 Δ g，v= 0）的绝对密度作为功率的函数作为其基准。尽管等离子体存在固有的空间不均匀性，但使用最小反应集的体积平均模型能够再现先前对O-绝对密度的测量，并在E-H切换过程中推断出电子温度和数密度的物理合理值。时间分辨发射测量返回的值为0.2的壁损失系数为O 2（B 1 μ g+）;因此，O 2（B 1 μ g+）的数密度（至少）比O 2（a 1 Δ g）小一个数量级。
The absolute number density of ground state oxygen atoms, O (3 P), present in a 100 mTorr oxygen plasma has been determined as a function of operating power using cavity ringdown spectroscopy (CRDS). The dissociation fraction increases by an order of magnitude from∼ 0.8% at 50 W to 8% at 250 W and reflects a similar increase in the electron density over this power range. Emission spectra show that the E–H switchover is accompanied by increased rotational heating of O 2 and this behaviour is also observed in the translational temperatures determined by fitting the Doppler limited O (3 P) CRDS data. The measurements are contextualised via a volume averaged kinetic model that uses the measured absolute densities of O (3 P) and O 2 (a 1 Δ g, v= 0) as a function of power as its benchmarks. Despite the inherent spatial inhomogeneity of the plasma, the volume averaged model, which uses a minimal set of reactions, is able to both reproduce previous measurements on the absolute density of O− and to infer physically reasonable values for both the electron temperature and number density as the E–H switch over is traversed. Time-resolved emission measurements return a value of 0.2 for the wall loss coefficient for O 2 (b 1 Σ g+); as a consequence, the number density of O 2 (b 1 Σ g+) is (at least) one order of magnitude less than O 2 (a 1 Δ g).