Atmospheric helium capillary dielectric barrier discharge for soft ionization: determination of atom number densities in the lowest excited and metastable States.
Atmospheric helium capillary dielectric barrier discharge for soft ionization: determination of atom number densities in the lowest excited and metastable States.
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DOI：
10.1021/ac403518s
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发表时间：
2014-01
影响因子：
7.4
通讯作者：
V. Horvatić;S. Müller;D. Veẑa;C. Vadla;J. Franzke
中科院分区：
文献类型：
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作者：
V. Horvatić;S. Müller;D. Veẑa;C. Vadla;J. Franzke
用光学发射光谱法测定了大气氦毛细管介质阻挡放电中产生的最低激发态2s 3S1、2s 1S、2p 3P0 J和2p 1P0的居群。测量了388、501、587和667nm线沿放电轴方向的发射强度。通过比较线核吸收效应的光学薄侧谱和端谱，确定了He态沿等离子体长度l的数密度n1的平均值，并计算了与实验条件相关的一系列n1L参数的理论剖面场。通过将实验数据引入计算曲线场，可以得到特定状态对应的n1L。发射曲线的测量是作为放电电压的函数在覆盖均匀和丝状DBD操作模式范围内完成的。由于受激原子密度沿等离子体分布的不均匀性，只有在非均匀性较小的均匀工作模式下才能得到n1的值。在所研究的状态中，数目密度的最大值为n1 av (2s 3S1) =（2.9±1.1）× 1013 cm - 3, n1 av (2s 1S) =（1.4±0.5）× 1013 cm - 3, n1 av (2p 3P0 J) =（1.1±0.4）× 1013 cm - 3, n1 av (2p 1P0) =（4.2±1.6）× 1012 cm - 3，它们代表了毛细管中沿血浆柱的平均种群。
The populations of the lowest excited helium states 2s 3S1, 2s 1S, 2p 3P0 J, and 2p 1P0 created in an atmospheric helium capillary dielectric barrier discharge were determined by means of optical emission spectroscopy. The emitted intensities of 388, 501, 587, and 667 nm lines were measured side-on and end-on with respect to the discharge axis. The comparison of optically thin side-on spectra with end-on spectra, which exhibited the absorption effects in the line kernels, enabled the determination of the average values of the number densities n1 in the considered He states along the plasma length L. The field of the theoretical profiles for a series of the n1L parameters pertinent to the experimental conditions was calculated for each line. By introducing the experimental data into the field of calculated curves, n1L corresponding to the particular state could be obtained. The measurements of the emission profiles were done as a function of the discharge voltage in the range covering homogeneous as well as filamentary DBD operation mode. Due to nonuniformity of the excited atom density distribution along the plasma, the values of n1 could be obtained only in the homogeneous operation mode where the nonuniformity was small. The following maximum values were found for the number densities in the investigated states: n1 av (2s 3S1) = (2.9 ± 1.1) × 1013 cm−3, n1 av (2s 1S) = (1.4 ± 0.5) × 1013 cm−3, n1 av (2p 3P0 J) = (1.1 ± 0.4) × 1013 cm−3, n1 av (2p 1P0) = (4.2 ± 1.6) × 1012 cm−3, and they represent the average populations along the plasma column in the capillary.