| dc.description |
A spark gap was designed and constructed to measure the time dependent arc resistance . The arc current was measured and the arc resistance calculated using the current and the other circuit parameters . Typical operating parameters were : unipolar pulse , 35 kV breakdown voltage , 30 kA peak current , and 1 .15 kJ total energy per shot . The dissipated arc energy was calculated from the arc current and resistance and found to be between 4 .5 % and 10 .5 % of the total energy . Arc resistance vs time curves were obtained for all possible combinations of three electrode materials (304 Stainless Steel , ACF -IOQ Graphite , and 3w3 Copper -Tungsten ) , three gases (Air , N2 , and SF6 ) , and three gas pressures ( 1 , 2 , and 3 atmospheres ) . Statistical analysis was performed on the resultant data . Essential results are : within the statistical and measurement errors , the resistance is independent of the electrode material . For each gas , R is approximately proportional to pd (pressure and gap distance ) . The constants of proportionality are (31 ± 7 ) mΩ / (cm bar ) for air , (47 + 15 ) mΩ / (cm bar ) for N2 , and (76 ± 17 ) mΩ / (cm bar ) for SF6 . |
|