Igniter for an air bag inflator

An inflator for a vehicle occupant restraint comprising:

• (a) gas generating material;
• (b) an igniter to ignite the gas generating material for producing a low brisance flame for igniting said gas generating material, said igniter comprising:
• (i) a container including means for defining an orifice in the container, said orifice having an orifice area;
• (ii) a rupturable closure means for closing said orifice;
• (iii) a particulate output charge in said container;
• (iv) a rapidly burning ignition charge material ignitable by a resistance wire for igniting said output charge;
• (v) means for retaining said output charge within said container so that said output charge is contiguous with said rapidly burning ignition charge material and so that the output charge occupies only a portion of the container, the container having a free volume in communication with the orifice, the free volume being equal to about 25% to 75% of the volume of the container;
• said output charge when ignited having a burn time in the range of 5 to 100 milliseconds;
• said orifice area being dimensioned to contain said output charge within said container following ignition until at least a substantial portion of said output charge ignites.