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Investigation of low tempersture plasma in gases and liquids Kamila Shojaa (24292871) PUREID: 687208131 Plasmas were generated at atmospherical pressure in liquid and gas.The plasma discharge in liquid was generated between two pin electrodes immersedin a CsCl solution, with an applied voltage of up to ∼ 7 kV. It was observed thatthe discharge develops in two distinct phases: a resistive phase where the liquid heatsup followed by an arc discharge where the resistance of the plasma is close to zero. The dominant emission observed in the CsCl plasma spectra were Balmer Hα and Hβlines, and a continuous black-body type background. The hydrogen lines exhibited significant broadening due to Van der Waals and Stark broadening. Lorentzian profileswere fitted to the Hα and Hβ lines to determine their widths, which allowed calculation of electron density and pressure. The highest electron number density ovbserved was 1018 cm−3 and the highestpressure observed was ∼ 1000 bar; these values were observed towards the beginning ofthe discharge; these values rapidly and smoothly declined during the discharge. Both the electron temperature and the blackbody temperature showed the same trend overtime delays. Another plasma was generated at atmospheric pressure using a spark gap dischargein air. This discharge was produced between two parallel plate brass electrodesseparated by a 1 mm gap, with an applied voltage of 4.5 kV. Two discharge modes were observed: streamer discharge and spark or transient spark discharge. The most prominent spectral emissions corresponded to atomic and ionic species of Zn and Cu. The electron temperature was determined from time-averaged and time-resolvedemission spectroscopic measurements from Boltzmann plots of Zn I lines. It was foundthat the time-averaged temperature of the electrons was reduced from 0.59 eV to0.41 eV by the introduction of an inductor into the driving circuit that stretched the discharge out in time. Time resolved emission spectra with the inductor also showed a trend towards lower electron temperatures, but electron temperature was found to vary during the discharge and not remain at a single value. Finally, plasma jets were generated using air and helium gases inside a glass tube, with electrode separations ranging from 1 to 9 mm. Two different electrode configurations were employed: a needle-to-plate electrode and a needle-to-ring electrodeplaced above the tube. The applied voltage varied depending on the type of gas andthe distance between the electrodes. Spark or transient spark discharges were observed for both gases. The duration of the discharge was also found to depend on the circuit configuration. In air plasma, the dominant emissions were molecular, atomic, and ionicnitrogen species, along with atomic oxygen lines. In helium plasma, the emissions were mainly from atomic helium and molecular nitrogen. Preliminary measurementsshow that the air plasma jet could be generated with an emission plume that extendedbeyond the ground electrode and that this jet has some bactericidal effect.<br><br><i>Thesis is embargoed until 31 July 2031.</i> 2026-10-01T16:14:02Z Text Thesis 10.17034/32805692.v1 https://figshare.com/articles/thesis/Investigation_of_low_tempersture_plasma_in_gases_and_liquids/32805692 All Rights Reserved Open Access after 2031-07-31