There are a wide array of methods available for dispensing [directed energy] such a discharge, from plasma weapons, lasers and phase weapons to modern Starfleet's phaser weapon, which fires particles called nadions. Another common energy discharge weapon is the disruptor, used by Klingons and Romulans. (TOS; TNG; DS9; ENT)--Directed Energy Weapon - Memory Alpha
Type 1 Phasers are the standard side arm of Starfleet officers. If the situation warrants it, Type 2 Phasers may be issued. Phaser Rifles are rarely issued during peace time. Starfleet phasers are far more versatile and expensive than the disruptors used by most other galactic powers. Rainbow Lasers are popular civilian weapons.
All these weapons use Beam Weapons skill to operate. A ready maneuver is required to change the setting (e.g. Base Cycle Stun to Light Heat), adjust the cone size (available for Base Cycle Stun and Heat settings only), or to set the RoF (e.g. selecting the maximum RoF to be 2 instead of 10).
There are two significant difference with this campaign setting and Star Trek cannon. Stunning is not automatic: there is a HT roll to resist and it can cause phaser burns. Disintegrate does not make you neatly vanish; it does tight beam burning damage.