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It is our endeavor to develop switching technology for the breakdown reliability and reproducibility at extremely high voltages above 1 MV. One of the key objectives of the endeavor is to derive precise breakdown criteria for use in high-voltage applications. We have developed empirical criteria by which the breakdown field strength of a high-pressure \SF6-filled spark gap can be computed. The validity of the computed result has been verified with several experimental data from different investigators. The computed result has shown good agreement in an extended range of pd (pressure times gap distance) and field enhancement factor of the spark gap geometry. Furthermore, a spark gap has been designed and constructed with particular intention of generating a high-pulsed-power source in Pohang Accelerator Laboratory. In parallel, field modeling has been performed to verify the appropriate shape of the highly stressed insulator and electrode design in the spark gap and to evaluate their field enhancements. A series of breakdown voltage tests has demonstrated the function of the spark gap switch as intended up to 9 bars of \SF6. Aside from this, the limitation of the switching behavior has been examined with an aim of operating the designed spark gap to its maximum capability. [ABSTRACT FROM PUBLISHER]

It is difficult to predict or measure the breakdown strength of SF6 gas in the high pressure range. Therefore, it is hard to find reference data of the high pressure SF6 gas breakdown strength. This paper attempts to provide empirically a novel criterion for the estimation of SF6 gas breakdown strength in a spark gap switch. For this purpose, J.C. Martin's breakdown field strength of non-uniform gap in air and Kuffel et al's breakdown field strength by exploiting streamer criterion of uniform field in SF6 gas are adopted. The research is made for the empirical method of predicting the high pressure SF6 breakdown strength and compared results have been ascertained with several experimental data from different investigators in a wide range of pd (pressure times distance) and field enhancement factor (FEF). For further confirmation of the empirical approach, we have designed and developed a high pressure spark gap switch to be closely coupled to a high voltage PFN-Marx system. The designed spark gap switch operates above 1 MV. Our tests have verified the prediction of the breakdown strength of the SF6 filled spark gap switch in a pd range of 0.27-1.62 MPa . cm (2.7 to 16.2 bar.cm). [ABSTRACT FROM AUTHOR]

It is difficult to predict or measure the breakdown strength of SF6 gas in the high pressure range. Therefore, it is hard to find reference data of the high pressure SF6 gas breakdown strength. This paper attempts to provide empirically a novel criterion for the estimation of SF6 gas breakdown strength in a spark gap switch. For this purpose, J.C. Martin's breakdown field strength of non-uniform gap in air and Kuffel et al's breakdown field strength by exploiting streamer criterion of uniform field in SF6 gas are adopted. The research is made for the empirical method of predicting the high pressure SF6 breakdown strength and compared results have been ascertained with several experimental data from different investigators in a wide range of pd (pressure times distance) and field enhancement factor (FEF). For further confirmation of the empirical approach, we have designed and developed a high pressure spark gap switch to be closely coupled to a high voltage PFN-Marx system. The designed spark gap switch operates above 1 MV. Our tests have verified the prediction of the breakdown strength of the SF6 filled spark gap switch in a pd range of 0.27-1.62 MPa . cm (2.7 to 16.2 bar.cm). [ABSTRACT FROM AUTHOR]