Spectroscopic Emission from Argon and Nitrogen Microplasmas
Dr. Stephen Remillard, Physics
Many electronics use microgaps as tuning elements for high frequency operation.The residual gas inside these microgaps can breakdown into a plasma either unintentionally or by design. The breakdown condition and spectral emission of nitrogen and argon plasmas were examined under microwave excitation. The differences among the plasma discharges were studied in three different microgap ranges using nitrogen and argon. The breakdown condition was defined as the input power that ignites microplasma, and the breakdown condition exhibited three distinct pressures. These three ranges were: under 10 torr, multipactor branch, 10 – 300 torr, Paschen branch, and 300 – 700 torr, diffusion-drift branch. A high resolution diffraction grating spectrometer was used to test nitrogen and argon by exploring the emission spectra and by comparing the spectra from microgaps to large gaps across these three pressure domains, revealing suppression and enhancement of spectral peaks in the microgaps compared to large gaps. As examples, enhancement is shown in a gap of 15 microns and is then suppressed in a gap of 1.6mm. A similar peak suppression occurs in Argon at wavelengths of 591.2nm with a 4 -> 6 vibration transition and 419.8nm with a 2 -> 4 vibration transition.
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