DirectionVariation is randomly alter the emission angle at a certain amount, is it possible to set the angle fixed?

Variations are always randomly applied to avoid uniform repetitions and make effects looking more natural. If you want to spray particles into fixed directions, you could also rotate the emitter, for example, using certain rotation steps while emitting -or use a custom emission shape. If you define a diamond shaped line, for example, and set the useCornersOnly parameter to true and the useEmitterRotation parameter to false, particles should be emitted from the line's four corner points only and therefore into four different directions.