FSD supercharging is the process of flying into a high-energy relativistic jet of a neutron star or a white dwarf in supercruise with a Fuel Scoop equipped, which increases the FSD range for the next jump at the cost of slight damage to the Frame Shift Drive itself. FSD supercharging from a white dwarf gives a 50% (1.5x multiplier) range bonus, while doing the same with a neutron star provides a 300% (4x multiplier) bonus, effectively quadrupling a ship's range for a single jump. Note that supercharging is not an instant process, and the pilots may have to spend several seconds inside the jet for the effect to apply.
This is a risky process, as the high-energy jet of the star can fling the ship around and make it difficult to control, and disengaging supercruise while inside the jet will strain and inflict damage to a ship's modules and hull. Larger ships with greater mass are somewhat resistant to the jet's magnetic forces and can be easier to control during the process than smaller ships.
Independently-charted Neutron Highways can be used to traverse vast differences with far fewer jumps than the conventional method of travel. These routes usually involve using the supercharge acquired at one neutron star to jump directly to another system with a neutron star or close to it, and thereby chain supercharged jumps almost indefinitely until the destination is reached, provided the pilot can keep their FSD repaired and refuel with standard fuel scooping when necessary.
Once supercharged, the FSD will retain the charge until used or until fuel is scooped from a main sequence star. Repairing the FSD or signing out of the game does not affect the supercharge.