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The non-equilibrium ro-vibrational distribution functions of molecules in aplasma can heavily influence the discharge operation and the plasma-chemistry.A convenient method for measuring the distribution function is by means ofcoherent anti-Stokes Raman scattering (CARS). CARS spectra are measured in ans-pulsed plasma between two parallel, 1 mm spaced molybdenum electrodes innitrogen at 200 mbar with pulse durations of 200 ns / 250 ns and a repetitionrate of 1 kHz. The CARS spectra are analyzed by a fitting routine to extractinformation about the vibrational excitation of the nitrogen molecules in theplasma. It is found that during the discharge the vibrational distribution for$v \lesssim 7$ can be described by a vibrational two-temperature distributionfunction. Additionally, the electric field is measured by the E-FISH methodduring the discharge pulse. It is found to be constant in time after theinitial ionization wave with values close to 81 Td for the investigatedconditions. During the afterglow between two discharge pulses a more generalfitting approach is used to obtain the population differences of twoneighboring vibrational states. This allows to capture the more complexvibrational dynamics in that time period. The measurement results are discussedin more detail and compared to simple models in a companion paper.

Vibrational CARS measurements in a near-atmospheric pressure plasma jet in nitrogen: I. Measurement procedure and results