The accuracy of relativistic particle beam weapons and lasers is limited by the resolution of the firing ship's sensors:
P(hit) = r2 / (Δxr)2
The beam width is given by
rbeam = λ R / d
At this range the beam width of a 1 micrometre infrared chemical laser with a 2m beam director will be
rbeam = 17.5m
In contrast a 10nm wavelength x-ray laser with the same size director will have a beam width given by
rbeam = 0.175m
Clearly only the later will be of any use
Beam weapons come in two main types: lasers and particle accelerators. Lasers are subdivided into chemical and free-electron lasers. Particle accelerators are subdivided into charged particle beam and neutral particle beam weapons. Both varieties require an associated power storage device (usually an HPG) or a burst-mode power plant (usually a pulsed gaseous fission generator).
A third variety of beam weapon is the nuclear-pumped gamma ray laser. These are the major weaponry used in serious conflicts.
Particle beam weapons are 50% efficient.
All beam weapons consist of a beam source and a focusing array. The focusing array for lasers is similar to a telescope using the same wavelength as the beam; both varieties of particle beams are focused by magnetic lenses. Magnetic lenses are of much poorer quality than their optical counterparts and this is only partly compensated for by the short de Brogle wavelengths of the beam particles. Particle beam weapons thus have a shorter effective range than lasers, but the use of heavy ion beams at high currents means that they inflict much greater damage from a successful hit.
When a particle beam intersects a spacecraft hull it produces a shower of secondary radiation. The energy of the beam is adjusted so that the maximum of this shower is most likely to occur within the hull, thus depositing the maximum energy within the target. Making the particle energy too high results in wasted energy as the particles pass straight through the target.
It should be noted that at short range a reaction drive can be used as a very powerful weapon. The drive plume may be aimed with much less accuracy than even particle beams, so their have been few instances of vessels being attacked with fusion drives. Against slow targets such as stations, however, they are extremely effective.
The future of Ad Astra