TY  - THES
AU  - Hörsch, Julian Michael
TI  - Electron Temperature Measurements in Discharge Capillaries
IS  - DESY-THESIS-2022-009
PB  - Universität Hamburg
VL  - Masterarbeit
CY  - Hamburg
M1  - PUBDB-2022-01913
M1  - DESY-THESIS-2022-009
T2  - DESY-THESIS
SP  - 96
PY  - 2022
N1  - Masterarbeit, Universität Hamburg, 2022
AB  - The electron temperature of hydrogen and argon plasmas, that were produced at gas pressures of a few millibar and with electron densities in the range of 1×10<sup>15</sup> \textcm<sup>−3</sup> to 1×10<sup>17</sup> \textcm<sup>−3</sup>, were investigated. These working points are typical of plasma sources which are used in beam-driven plasma wakefield accelerators such as FLASHForward. The particular plasmas were produced with a high voltage discharge inside a sapphire capillary that allowed, by means of their transparency, optical emission spectroscopy measurements. To determine the electron temperature emission lines were measured and the Boltzmann plot method, which requires optical thin emission lines and partial local thermodynamic equilibrium (pLTE), applied. These requirements were discussed and it was shown that the argon plasma is likely to exhibit stronger deviations than the hydrogen plasma. In hydrogen the maximum electron temperature could be successfully determined to 1.6±0.40 \texteV and this with significantly smaller uncertainties than in previous measurements. For argon this method was less successful and yielded un-physical results. This was in agreement with possibly stronger deviations from the pLTE conditions for argon and necessitated the implementation of a more complex collisional radiative model (CRM) for the temperature determination. The temperatures resulting from the CRM approach were similar to those obtained with the Boltzmann plot analysis and could therefore not improve the results. With these first results this study has laid the ground-work for the electron temperature characterisation in discharge capillaries for FLASHForward, which is a key for improving electron density measurements, plasma modelling and future active plasma lenses.
LB  - PUB:(DE-HGF)3 ; PUB:(DE-HGF)19
DO  - DOI:10.3204/PUBDB-2022-01913
UR  - https://bib-pubdb1.desy.de/record/477117
ER  -