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Electrical energy conversion characteristics based on underwater high-voltage pulse discharge

Yan Dong, Chen Songbai, Wu Qiong, Zhang Fengxiang, Lai Lipeng, Chen Inchen

Journal of Power Technologies

2021

Vol. 101, nr 4

190--201

Underwater high-voltage (HV) pulse discharge mainly involves the process of HV discharge, breaking down water and releasing huge amounts of electrical energy, which is then rapidly converted into plasma. The plasma expands and creates shock waves and bubble pulsation effects. These effects are the main ways in which electrical energy transfers into mechanical energy. A breakdown process analysis model and an experimental method are proposed with a view to revealing the energy conversion characteristics during underwater pulse discharge and to understand the basic physical process. A plasma channel model was established in combination with the existing fundamentals of electricity and theoretical analysis. In addition, the discharge process was analyzed, along with shock wave and bubble pulsation action characteristics, on the basis of an underwater pulse discharge experiment. Meanwhile, theoretical analysis revealed the basic physical process involved in the electrical energy conversion effect. The results demonstrate the following: (1) The vaporization-ionization" breakdown model divides the breakdown process into three stages (i.e., heating effect, breakdown detonation and mechanical energy effect stages); (2) the heating effect stage is a phase prior to breakdown, which possesses significant heating characteristics and generates initial plasma; (3) a large electric current (104A) during the breakdown process heats the plasma channel to a high-temperature, where it becomes dense; this condition is followed by an instant decrease in channel resistance; the breakdown current peak depends on the residual voltage at the moment of breakdown; (4) during the breakdown detonation stage, discharge breakdown occurs, along with electric arc detonation. After the heating gasification process, when the electrical field intensity is suficient, the high-temperature HV plasma rapidly expands outward, resulting in a rapid conversion from electrical energy to mechanical energy. Thus, shock waves are formed, followed by bubble pulsation. The proposed method provides a good prospect for the application of underwater HV pulse discharge technology in the field of engineering.

Deposition of thin films based on silica on polycarbonates by pulsed dielectric barier discharge

Opalińska T., Ulejczyk B., Karpiński L., Schmidt-Szałowski K.

Polimery

2004

T. 49, nr 4

257-263

Wymienioną w tytule cienką warstwę osadzano z mieszaniny gazowej helu, tlenu i tetraetoksysilanu (TEOS) (tabela 1) w aparaturze przedstawionej schematycznie na rys. 1-3. Proces prowadzono pod ciśnieniem atmosferycznym bez podgrzewania podłoża poliwęglanowego (PC) w postaci płytek. Zbadano wpływ parametrów procesu, mianowicie sposobu ułożenia płytek PC w reaktorze (rys. 7, 9 i 10), składu gazu plazmotwórczego (rys. 8) oraz natężenia prądu w pojedynczym impulsie wyładowania na szybkość osadzania. Szybkość ta rosła od 3,4 do 40,8 nm/min wraz ze wzrostem natężenia prądu w pojedynczym impulsie od 50 do 100 A. Stwierdzono, że w procesie tworzenia cienkiej warstwy konieczna jest obecność tlenu w gazach plazmotwórczych, przy czym nadmiar tlenu powoduje zmniejszenie szybkości osadzania z 14,9 do 6,0 nm/min gdy stężenie tlenu wzrasta od 5 do 20 % obj. (tabela 2). Budowę chemiczną oraz morfologię osadzonych warstw scharakteryzowano metodami FT-IR (rys. 4), AFM (mikroskopia siła atomowych, rys. 5) oraz SEM (rys. 6). Cienka warstwa składała się z następujących pierwiastków: Si, C, O oraz H i charakteryzowała się gładkością, a także przezroczystością.

The process of thin organo-silica film deposition on polycarbonate in pulsed dielectric barrier discharge was studied. Thin film was deposited from the gas mixture comprising helium, oxygen and tetraethoxysilane under atmospheric pressure without pre-heating of polycarbonate plate. Influences of process parameters, namely the current of single pulse of discharge, PC plate arrangement and position, and plasma-generating gas composition on the deposition rate were investigated. Deposition rate increased from 3.4 to 40.8 nm/min when the current of single pulse increased from 50 to 100 A. The presence of oxygen in plasma-generating gas was necessary to thin organosilicon film forming, but the excess of O2 concentration caused decreasing of film deposition rate, for example: deposition rate was 14.9 or 6.0 nm/min when concentration of O2 was changed from 5 to 20 % by vol. In the films, the following elementaly composition (Si, C, O, H) and morphology of deposited films were characterized.