Fuel and jumping


When you consider the original lanthanum grid, and the new localized field, in case of breaks, nobody knows.
There was no "original Lanthanum grid", it was a MegaTraveller invention and not present in CT or any version since MegaTraveller.
These are accumulators, sweeping up exotic particles captured by a canopy and removing the need to carry separate fuel for the jump drive. This charge is released in a single spike to power a jump drive; collectors cannot be used for normal ship operations.

Collectors become available at TL14. They consume 1% of a ship’s tonnage multiplied by the maximum jump number its drive is capable of, plus five tons. They cost MCr0.5 per ton.

It takes a week of normal space travel to fully charge an accumulator and accumulators do not work in jump space, in an atmosphere or on a ship expending thrust.
Yes, in the jump drive coils.
Lanthanum: A rare earth element, the first of the inner transition metals. Vital
to the construction of the inner coils of interstellar jump drive units.