Water Transmission Line Resistance To High Voltage Breakdown

As an insulating dielectric, water has as high relative dielectric constant as 80 and the quality of being self-healing. These characteristics make water an excellent choice for building large capacitors. Loading pressure on water is one of the most successful techniques to increase the field strength of water. High-pressure water transmission line is one important investigation direction on transmission line miniaturization.A design of water breakdown experiment model, and a water breakdown experiment on pressure effect based on this model design are described in this paper. Experiment results indicate that: water breakdown electric field reaches 1350±140kV/cm under the conditions of 0.15cm2 effective area, 118ns effective breakdown time, and 10atm hydrostatic pressure, and water breakdown electric field increases 8% as water hydrostatic pressure increases from atmospheric to 10 atm. Then, experiment errors are analyzed and experiment results are interpreted theoretically.A Blumlein transmission line with parameters of 1MV voltage, 5Ω impedance, and 60ns pulse duration at the conditions of 10 atm is designed in this paper. This PFL has the length of 100.6cm and is made of an inner cylinder with 9.15cm radius, a middle cylinder with 16.4cm radius, and an outer cylinder with 19.3cm radius. The volume of such a PFL is 46% smaller than that at the condition of I atm. As a result, loading high pressure on water is successful in transmission line miniaturization.A 5 stage pulse forming network with parameters of 8Ω, 100ns, and 500kV is designed in this paper. The simulation indicates that the rips of the top of pulse is about 6% on account of too low lumped inductances which is difficult to be made, and the whole volume is about 0.15m2. But the volume of Blumlein transmission line designed with the same pulse designing parameters as half big as that of PFN. Therefore, investigation on short pulse PFN is hardly interesting in transmission line miniaturization.Finally, all work in this paper is summarized, water breakdown experiment model on the basis of the experiment results and present conditions has been improved, and coaxial transmission line breakdown model is present in detail.