TY - GEN
T1 - Liquid nitrogen breakdown due to thermally generated bubbles in plane-plane electrode geometry
AU - Sauers, Isidor
AU - James, Randy
AU - Ellis, Alvin
AU - Tuncer, Enis
AU - Polizos, Georgios
AU - Pace, Marshall
PY - 2010
Y1 - 2010
N2 - Liquid nitrogen is used as the cryogen and dielectric for many high temperature superconducting, high voltage applications. When a quench in the superconductor occurs, bubbles are generated which can affect the dielectric breakdown properties of the liquid nitrogen. Experiments were performed using plane-plane electrode geometry where bubbles were introduced into the gap through a pinhole in the ground electrode. Bubbles were generated using one or more kapton heaters producing heater powers up to 30 W. Pressure was varied from 100-250 kPa. Breakdown strength was found to be relatively constant up to a given heater power and pressure at which the breakdown strength drops to a low value depending on the pressure. After the drop the breakdown strength continues to drop gradually at higher heater power. At low heater power the breakdown strength increases with pressure nonlinearly saturating at around 200 kPa, while the breakdown strength at high heater power increases according to Paschen law indicating a gas gap breakdown which is believed to be due to the formation of vapor bridge in liquid nitrogen. The heater power at which the breakdown strength changes from that of liquid nitrogen to that of gas nitrogen increases with increasing pressure. The data can provide design constraints for high temperature superconducting fault current limiters so that the formation of a vapor bridge can be suppressed.
AB - Liquid nitrogen is used as the cryogen and dielectric for many high temperature superconducting, high voltage applications. When a quench in the superconductor occurs, bubbles are generated which can affect the dielectric breakdown properties of the liquid nitrogen. Experiments were performed using plane-plane electrode geometry where bubbles were introduced into the gap through a pinhole in the ground electrode. Bubbles were generated using one or more kapton heaters producing heater powers up to 30 W. Pressure was varied from 100-250 kPa. Breakdown strength was found to be relatively constant up to a given heater power and pressure at which the breakdown strength drops to a low value depending on the pressure. After the drop the breakdown strength continues to drop gradually at higher heater power. At low heater power the breakdown strength increases with pressure nonlinearly saturating at around 200 kPa, while the breakdown strength at high heater power increases according to Paschen law indicating a gas gap breakdown which is believed to be due to the formation of vapor bridge in liquid nitrogen. The heater power at which the breakdown strength changes from that of liquid nitrogen to that of gas nitrogen increases with increasing pressure. The data can provide design constraints for high temperature superconducting fault current limiters so that the formation of a vapor bridge can be suppressed.
UR - http://www.scopus.com/inward/record.url?scp=79952905347&partnerID=8YFLogxK
U2 - 10.1109/CEIDP.2010.5724070
DO - 10.1109/CEIDP.2010.5724070
M3 - Conference contribution
AN - SCOPUS:79952905347
SN - 9781424494705
T3 - Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP
BT - 2010 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2010
T2 - 2010 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2010
Y2 - 17 October 2010 through 20 October 2010
ER -