High voltage vacuum tube (9) with an anode (3) and a cathode (4), the anode (3) and/or the cathode (4) being electrically insulted by means of an annular insulator (21/22). The annular insulator (21/22) is designed arched once, humped in direction of the vacuumized inner space (6), the arch having in the direction of the vacuumized inner space (6) a sloping front area (31) and two lateral areas (30/33). The sloping front area (31) of the insulator (22) of the anode (3) slopes toward the disc center (7) of the insulator (22), while the sloping front area (31) of the insulator (21) of the cathode (4) slopes away from the disc center (7) of the insulator (21).