Abstract: A spark gap discharger includes a barrier structure having elements that reduce or prevent the buildup of a conductive surface path between electrodes due to the deposition of ablated electrode material on the inner walls of the spark gap chamber. The insulator body structure of the spark gap discharger includes one or more concentric insulator sleeves positioned inside the spark gap so that metal ablated from the electrodes during firing preferentially deposits on the insulator sleeve(s). The sleeve(s) are arranged such that a conductive path due to metal deposition on the inner walls of the body structure between one electrode and the other cannot form. Spark gap dischargers according to aspects of the present invention advantageously exhibit longer useful lifetimes than prior art spark gap dischargers.