Evaluation of arc damage to power triode grid wires

Experiments involving aluminium foil damage tests and a simulated grid structure were performed in order to relate such tests to the minimum energy required to damage the grid structure of a type A-15186C tube. In the case of foil tests conducted in air, it was shown that the energy in a particular fault is related to the foil hole size and is in close agreement with engineering calculations and published data. In a vacuum arc gap the damage is much less than indicated by the air foil test. The arc becomes mobile and the energy dissipation appears widespread over the surface area rather than being concentrated or anchored in a spot. (The damage or hole size was much smaller than obtained from engineering calculations.) With energies up to 100 joules and charges up to 0.25 coulombs, more than 100 pulses were required to damage simulated grid wires to the extent where breakage occurred. On a single shot basis, energies in excess of 3000 joules were required to produce damage.