Paschen Testing on W7-X Coils and Components in the BNN Test Facility

During the fabrication of the coils for the Wendelstein 7-X experiment the need for pressure dependent high voltage testing—Paschen tests—of the coils and components arose. These tests ensure the safety of the coils in case of an emergency shutdown due to a break in the vacuum of the cryostat. For that purpose the vacuum test facility at Babcock Noell Nuclear was modified in order to perform these tests. It is now possible to test coils and their components up to 17 kV and for pressures below
$1.0 cdot 10^-3 mbar$
. Completed coils, winding packs before insertion in the case and also several components have been tested up to now. It has been demonstrated that these Paschen tests are a powerful tool to detect insulation defects. The paper shows the effort which has been taken to set up the test facilities. It will show the preparation of the components under testing as well as present and discuss the results obtained up to now.