The electric field in plasmas governs ignition, electron heating, and excitation of atoms and molecules. In particular tailoring the ro-vibrational excitation of molecules depends to a large extent on the particular waveform of the electric field in the plasma. In transient atmospheric pressure plasmas the temporal development of the electric field can be complex due to ignition, ionisation waves, space charge development or surface charging. It is therefore of key importance for the investigation of these systems to have reliable measurements of the temporally and spatially resolved electric field. In many cases the crucial timescale is of the order of ns or sub-ns. On a timescale of about 4 ns laser electric field measurement based on a CARS like scheme has been developed in recent years and applied to a variety of atmospheric pressure plasmas. Here this scheme will be extended into the sub-ns regime (temporal resolution of about 100 ps). This will provide sufficient temporal resolution for all pulsed or alternating electric field driven discharges of relevance in the Collaborative Research Centre. In addition to allowing high temporal resolution also the sensitivity will be enhanced due to higher laser pulse intensities. The technique will be applied to the investigation of a wide spectrum of transient discharges and combined with other diagnostics, in particular measurements of molecular excitations.
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