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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]

Radial multichannel pseudospark switches for extremely high-charge transfer were designed, constructed, and tested. The characteristics of the switches were measured for different electrode geometries and materials in hydrogen and helium as function of gas pressure. The switches were operated in a 100-kJ capacitor bank and conducted an effective charge up to 31 C. A sealed-off radial multichannel pseudospark switch was also manufactured and tested with a 300-kJ capacitor bank. The switch was successfully tested up to 105-kA peak current and 78-C charge transfer. The experimental results demonstrated that a radial multichannel pseudospark switch with SiC electrodes and triggered by a high dielectric trigger has the capability of extremely high charge transfer under pulsed operation. [ABSTRACT FROM AUTHOR]