FIG. 2 is an enlarged view of a part of the electrode arrangement 100 of FIG. 1, illustrating the electrical field strength in the electrode arrangement in the vicinity of triple points 201 between the first electrode 110 and the first spacer element 140. The first electrode 110 is provided on a first electric potential different from a second electric potential of the second electrode 120. For example, at least one of the first and second electrodes is set on a high voltage potential. Since the first conductive shield 150 is electrically connected to the first electrode 110 via the contact assembly 160, also the first conductive shield 150 is provided on the first electric potential of the first electrode 110. Accordingly, the electrical field strength in the vicinity of the triple points 201 can be reduced (illustrated by the enlarged distance between adjacent electric field lines 202 in the vicinity of the triple points 201, providing a field reduction region 203 near the triple points 201).

The electrical field lines 202 are bent away from the first recess 112 in which the first spacer element 140 is placed toward the space beyond the first conductive shield 150. A field enhancement region 204 may be generated in a space between the first conductive shield 150 and the second electrode 120. By appropriately choosing the depth and shape of the first blind hole and the first conductive shield in the first spacer element 140, the maximum electrical field strength in the vicinity of the first spacer element 140 can be reduced, and the risk of arcing can be decreased.