The beam is not the worst thing about putting a laser on a warship, however; the main difficulty is in getting the ship to act like both a power plant and a heat sink simultaneously.
It is that business that has marked the new direction of the Navy with the Mk 5 Mod 0 HELIOS, a 60 kW-class laser which is being integrated with Aegis and has been fitted on USS Preble. The HELIOS is not bolt-on because it is integrated into the combat system of the ship and therefore its track data, direction and engagement logic coexists in the same ecosystem as the radar image and other weapons. Integration increases the upper limit of directed energy capability of a ship, but it also squeezes the margins in other areas: electrical headroom, chilled water, equipment-room temperatures, and even scheduling of other high-demand loads.
The engineering reality that was noted in the Navy laser reporting is the warning of Rear Adm. Ron Boxall, which says: I will force the Navy to either trim it off or I would feel compelled to think very aggressive power management. Whether there is fuel to produce electricity is a question largely irrelevant to an Arleigh Burke, whether the ship can produce sufficient power when required and channel it where required, and then take off the heat there comes with it is the question. Flight III destroyers bring in extra sensor capacity (in particular, SPY-6) and, as the class increases generation capacity (usually said to be three 4,000 kW ship-service generators), the additional electronics become additional waste heat that must dissipate in chilled-water loops and, finally, be discarded over the side. A single beam, as one analysis has it, was only the tip of a fairly large in-board energy and thermal system, a phrase attributed to Rear Admiral Fred Pyle in a CRS compilation, and also quoted by fleet officials in saying lasers are a SWaP-C issue, not yet a weapons issue.
Then comes the ocean itself. A laser located on board a ship has to force energy through a near-surface layer which is loaded with water vapor and salt particles, which absorb, scatter, and defocus laser energy. However, the quality and intensity of the beam at the aim point may deteriorate with the increase in the path length even with the target in sight. Above higher powers, the self-imposed penalty of thermal blooming is the beam warming the air it is passing through, which in turn is a lens spreading the spot and decreasing the damage rate, particularly in constant-bearing, “down-the-throat” shots.
Smoke is an even more disagreeable form of stressor, as it goes at both pillars simultaneously: physics and fire control. Obscurants may hasten to bloom and decrease effective range, in addition to making the precision problem more complex. The naval laser effects are not instantaneous as a proximity-fuzed interceptor can be; the beam has to linger over the target by many seconds to accomplish a destruction mechanism, and multiples of seconds may be magnified exponentially in a raid situation. According to technical discussion of obscurants and maritime lasers, a smokescreen increases the difficulty of making pinpoint aim, even when other sensors are still able to provide a track, and where fresh smoke may still be entering the line of sight as targets and winds change.
These constraints become tactics as swarming threats. One high-energy laser is typically used to interact with one target at a time, and the target cycling capabilities of the ship are not only limited by dwell time but also by thermal dissipation i.e. how fast the heat can be dissipated by the laser modules, power conditioning and beam control apparatus without throttling. It is because of this that the talking point of the “deep magazine” must have an asterisk: lasers can theoretically continue firing as long as power is available, but in practice they are rationed by the availability of power and cooling on shipsboard under real operational conditions.
The long-term implication can be traced in the map of development of the Navy itself. Existing fleet systems like HELIOS are in tens-of-kilowatts drone, small-craft, sensor-effect scale, and higher-end systems are targeting the missile-defense problem set. The work of the Navy in HELCAP, outlined in budget documents, aims at a prototype featuring a 300 kW+ nimbus laser source and beam-control improvements to be used in challenging crossing engagements, as well as atmospheric correction and precision tracking in clutter. They are not aspirational marketing phrases and rather checklists of living through precisely what shipboard lasers despise most: messy air, bright backgrounds, and numerous fast movers.
In the meantime the fatal examinations are routine and nautical salt haze, sea spray, smoke, and the time-table struggles within the hull. Ship lasers have yet to reach the next level of demonstrating that they can burn a drone, and then demonstrate that they can continue to burn a drone when the rest of the beam is in their way.
