Analysis of the Dielectric Characteristics of Gaseous Nitrogen According to Various Temperatures and Pressures for a Magnet System

作者：Nam Seokho; Lee Woo Seung; Lee Hongseok; Kang Jong O; Kim Junil; Mo Young Kyu; Bang Seungmin; Lee Onyou; Kang Hyoungku^*; Ko Tae Kuk

来源：Journal of Superconductivity and Novel Magnetism, 2017, 30(8): 2347-2352.

DOI：10.1007/s10948-016-3753-2

• High voltage
• Dielectric
• Breakdown voltage
• Partial discharge inception voltage
• Field utilization factor

Gaseous nitrogen (GN(2)) is used as an insulation and pressurization material for developing a high-voltage superconducting magnet system utilizing liquid nitrogen (LN2) cooling. In a LN2 cooling system, current leads for a high- voltage superconducting magnet are exposed to GN(2) to temperatures that can range from 65 to 300 K. Therefore, a study on the electrical breakdown and partial discharge inception voltage test was performed considering the temperature and pressure variation of GN(2). The dielectric characteristics of GN(2) were observed to improve as the temperature and pressure increased. In addition, the partial discharge inception voltage was similar to the behavior of dielectric breakdown voltage with respect to temperature and pressure. To confirm a functional relationship between the breakdown voltage and effect of the electrode surface area, experimental results were summarized using a field utilization factor. The dielectric breakdown voltage was found dependent on the field utilization factor. Consequently, the dielectric breakdown voltage of GN(2) could be expressed as a function of field utilization factor according to temperature and pressure.