Measurement of the temporal evolution of electron density in a nanosecond pulsed argon microplasma: using both Stark broadening and an OES line-ratio method

• Published in: Journal of physics. D, Applied physics Vol. 45; no. 29; pp. 295201 - 1-11
• Main Authors: Zhu, Xi-Ming, Walsh, James L, Chen, Wen-Cong, Pu, Yi-Kang
• Format: Journal Article
• Language: English
• Published: IOP Publishing 25.07.2012
• Subjects: Afterglows; Argon; Electron density; Evolution; Microplasmas; Nanocomposites; Nanomaterials; Nanostructure
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/45/29/295201

The temporal evolution of electron density in a nanosecond pulsed argon microplasma is measured using a combination of Stark broadening and the optical emission line-ratio method. In the initial discharge period (0-100 ns), the electron density can reach as high as ∼1018 cm−3. It decreases to ∼1017-1016 cm−3 in the early afterglow period (100 ns-1 µs after the ignition) and ∼1016-1013 cm−3 in the late afterglow period (1-20 µs). It is demonstrated that the optical emission spectroscopy (OES) line-ratio method can obtain the electron density in the range 1013-1016 cm−3, while in the range 1016-1018 cm−3, the Stark broadening technique with argon 2p-1s lines (in Paschen's notation) is a better choice. These results are in good agreement with those from the Stark broadening technique with hydrogen Balmer lines. Finally, a possible mechanism for such a density evolution is briefly discussed.