This is a more advanced version of recharging ray-class spells. With one chain recharge, you replenish some energy to target item and also to some others as well, as the ray will jump several times to other items until its power is spent. So it has significant advantage of recharging more items at once but at a cost of smaller amount of energy being replenished to each affected item.

See also: lesser chain recharge, minor recharging ray, minor recharging burst