van der Jjam Joost Mullen

Coherent and incoherent Thomson scattering on an argon/hydrogen microwave plasma torch with transient behaviour

A new method of processing time-integrated coherent Thomsonnscattering spectra is presented, which provides not only thenelectron density and temperature but also information about thentransient behaviour of the plasma. Therefore, it is annalternative to single-shot Thomson scattering measurements asnlong as the scattering is coherent. The method is applied to anmicrowave plasma torch operating in argon or a mixture of argonnwith hydrogen at atmospheric pressure. Electron densities up ton8.10(21) m(-3) (ionization degree above 10(-3)) were observed,nwhich is more than two times higher than presented in earliernworks on comparable discharges. Additionally, a parametricnstudy with respect to the argon/hydrogen ratio and the inputnpower was carried out and the results are discussed togethernwith earlier Stark broadening measurements on the same plasma.