Switching devices as follows: a. Cold-cathode tubes, whether gas filled or not, operating similarly to a spark gap, having all of the following characteristics: 1. Containing three or more electrodes; 2. Anode peak voltage rating of 2.5 kV or more; 3. Anode peak current rating of 100 A or more; and 4. Anode delay time of 10 μs or less; b. Triggered spark-gaps having both of the following characteristics: 1. Anode delay time of 15 μs or less; and 2. Rated for a peak current of 500 A or more; c. Modules or assemblies with a fast switching function having all of the following characteristics: 1. Anode peak voltage rating greater than 2 kV; 2. Anode peak current rating of 500 A or more; and 3. Turn-on time of 1 μs or less.