How do glows on a simple particle look like? If they look ok ( should look better than on a whole mesh coz it's simpler ), make your particle emiter spawn a lot of particles, so basically that creates a continuous stream of fire. With some randomness, it can look very cool ( not a pure, straight beam, but more like a wavy fireburst ).
In the worst case, create a nice glow map, an opacity map to go with it, crank up the selfillumination to 100%, and use the map on the particles, that will do about the same ( if possible, add some color blend so all the particles blend with each other ).