München 2019 – wissenschaftliches Programm
P 9.1: Hauptvortrag
Dienstag, 19. März 2019, 11:00–11:30, HS 21
Laser diagnostics of plasmas using fs- and ps-lasers — •Stephan Reuter — Princeton University, MAE-Department, Princeton, USA — Lublin Technical University, Lublin, Poland
Dynamics in plasma jets at atmospheric pressure span orders of magnitude in time scales, ranging from picosecond (ps) time scales of electron dynamics and energy transfer to heavy particles, to mass transport on a micro- and millisecond time scale by convection and diffusion into open atmosphere. Recent advances in ultrafast laser diagnostics, adapted from methods developed for combustion and aerospace engineering, allow highly resolved plasma diagnostics: Picosecond time and micrometer space resolved electric field measurements were recently achieved using a femtosecond (fs)-laser sheath in a plasma jet effluent: Electric field induced second harmonic (E-FISH) light generation is utilized to quantify the electric field induced by the fast ionization wave of the plasma jet. Comparing fs-1D resolved to ps-point wise measurements shows the potential of fs-E-FISH. Fs-lasers can also be used for recently developed fs-electronic excitation tagging (FLEET) to study the plasma jet's gas flow field into open atmosphere. Quantitative 1D gas velocity vector fields are determined by using the emission of excited nitrogen molecules as tracer. The great potential as well as challenges of ultrafast lasers for plasma diagnostics conclude the talk. Funding by Alexander von Humboldt Foundation and Princeton University is gratefully acknowledged.