Relativistic plasma weapons, or p-beams, use a particle accelerator to produce pulses of high energy, relativistic protons. To keep these from rapidly defocusing due to their mutual electric repulsion, a pulse of electrons is injected with the protons going the same speed and direction to produce a diffuse hydrogen plasma moving at relativistic speeds. The protons have 2000 times the mass of the electrons, so they are responsible for most of the energy of the beam. For this reason, p-beams are sometimes called proton beams.
In air, the electrons will be stripped from the plasma beam, leaving a beam of relativistic protons. These will self-focus in the same way as an electron beam. Protons are more stable than lighter electrons, but Acc is still only 3/5 normal. If using the Minute of Angle optional rules from GURPS Tactical Shooting pg. 32, effective skill is capped at 22 + 2×Acc.
When high energy protons encounter matter, they suffer continuous energy loss like all charged particles. However, most of the energy dumped into the matter comes when a proton smacks directly into a nucleus. These protons carry enough energy to shatter a nucleus and create a shower of mesons in the process. The nuclear fragments and charged particles rapidly dump their energy into the surrounding matter. In addition, the lighter or uncharged nuclear fragments produce a spray of radiation - neutrons, pions, muons, and gamma rays - that will cause radiation damage to anything nearby. These nuclear collisions are discrete processes that remove the protons from the beam, and and so p-beams are treated as radiation beams with both discrete and continuous energy deposition. They cause four damage increments of 30 basic damage before continuous ionization slows the beam to a stop. The radiation damage multiple is 100.
When using the advanced rules from GURPS Tactical Shooting, the following changes to the rules are used to reflect how plasma beams travel differently from bullets:
|TL||Weapon||Type||Damage||Acc||Range||Mass (kg)||ROF||Shots||Min ST||Bulk||Rcl||Cost||LC|
|12||Light P-Beam Cannon||Beam+1||30⊗4 (∞)||15+4||800 km/3000 km/50000 km/-||30/0.7||10||1000||21M||-10||1||40 k||1|
|12||Medium P-Beam Cannon||Beam+2||30⊗4 (∞)||15+4||1800 km/7000 km/110000 km/-||80/1.5||10||1000||32M||-10||1||90 k||1|
|12||Heavy P-Beam Cannon||Beam+10||30⊗4 (∞)||15+4||60000 km/250000 km/3500000 km/-||15000/300||4||400||424M||-10||1||18 M||1|
Light P-Beam Cannon: A beamer cannon used against light vehicles. Skill: Gunner (Beams). Aperture 12 cm. Depth of focus multiplier 0.4. Beam energy 15 kJ. Energy used per shot 15 kJ. Extra power cell 0.7 kg, $35.
Medium P-Beam Cannon: A rapid-fire vehicular beamer cannon. Skill: Gunner (Beams). Aperture 20 cm. Depth of focus multiplier 0.35. Beam energy 30 kJ. Energy used per shot 30 kJ. Extra power cell 1.5 kg, $80.
Heavy P-Beam Cannon: A large vehicle mounted beamer cannon. Skill: Gunner (Beams). Aperture 30 cm. Depth of focus multiplier 5. Beam energy 15000 kJ. Energy used per shot 15000 kJ. Extra power cell 300 kg, $15000.
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