By "pulse" I mean a single peice of the beam the game uses to determine the length. I think how beams work in FS2 is that they fire a continuous stream of hitscan (that is, instant-hitting) projectiles in a straight line to gradually do a large amount of damage over time (that time being the lifespan of the beam). The projectiles you fire through the cheat weapons are single pieces of the relevant beam.
This, however, is just what I think. I'm not sure if beams work any differently, but if they worked this way that would explain the large particle affect much suiting of a full sized beam comming out of such a tiny projectile.