Irrlicht Engine

I created smoke effect in my scene.Now I need cancel the effect when I press a key.I don't know how to stop particle emitter creating particles.

I want to control the particle system creating particle.
when I press 'A' it creat particles,press 'B' it don't create particles any more.

you can set the emitter 0.

ps->setEmitter(0);

and it will stop the particles, but doesn't destroy the system. if you wanna destroy it, you have to do it manually, or make an animator for it ( i made one before xD isn't so hard)