Make Particle emit straight beam - or Trail on object that only moves side to side?

Hi everyone, I'm going for this effect where a particle is emitted from an object over time, and when the object moves the particle moves. I can achieve this with a ball like particle if I turn the Rate over time up, but it looks chunky, and not like a smooth beam.

Is there a way to make the particle emitter emit a beam like in the image below? Maybe the solution is to have a Trail emitted from the object (which would need to be stationary, other than some side to side movement)? Any ideas?

Thanks!