ETC plasma ignition for modular artillery charges

At the 155 m artillery gun the ignition of the modular charge set-up is realized by a conventional jet igniter installed in the gun breech in combination with ignition material arranged in each single charge module. Up to six modules are ignited this way. By the number of modules the range of the gun can be modified. The ignition power is mainly adjusted to the maximum number of modules in order to stay within the pressure limits of the gun. By reducing number of modules the ignition power is reduced also. A compensation of the increasing volume in the charge chamber, which is not filled with propellant, by increasing the ignition power, cannot be realized in the conventional set-up. This effect limited the number of ignitable modules to two and urged the development of a so called "base module" with a different propellant and grain size in this module to achieve ignition in the case of low range applications. The idea of realizing a so-called "unicharge" had to be given up. The replacement of the conventional igniter with an ETC plasma-jet igniter opens the possibility to adjust the ignition power to the number of charge modules to be applied in the firing. The set-up of the modules does not have to be changed. The plasma-jet interacts with the ignition material in the modules. A proper design of the plasma-jet igniter leads to the generation of long plasma-jets reaching all modules, which are arranged in the charge chamber. In order to perform first investigations on the performance of this technology a 155 mm ignition simulator was modified and experiments with conventional charge modules were performed. With electric energies of only 5 kJ the safe ignition of even one module was demonstrated regardless of the position of this module in the charge chamber. Pressure rise times were significantly shorter that obtained from the conventional ignition. The paper presents the basic set-up of the plasma-jet igniter and the experimental set-up. The results of the ignition tests are described and discussed.