Direct Energy Weapons, DEW (part 3/3): considerations on systems and prospects for use

(To Stefano Avolio)
02/09/21

In previous articles we have presented the principles of possible DEW systems and we have dwelt on illustrating and analyzing the operating principles, listing the problems to be solved and describing prototypes developed for HPM and HEL, which are the two most promising types of systems.

Let us now try to present, as a final moment of synthesis, some considerations on the type of scenario that awaits us in the coming years.

An first consideration is related to the use cases of DEW weapon systems, which are multiple for Lasers (anti-ship, anti-aircraft, anti-missile, anti satellite, anti drone, etc., while considering that over time it will be necessary to find out if one type of use will become prevalent) but are more limited for HPM-DEW.

The reason is quite simple: the frequencies involved are different, and the directionality of the beam is therefore decidedly favorable to the Laser.

But the reduced directionality makes the HPM-DEW systems more suitable to face close and multiple threats (example: swarms of drones) or even to reduce the threat of groups of individuals (dissuasion systems in areas with hostile presences, see example the Active Denial System, ADS1). The Laser, on the other hand, is more suitable for dealing with punctual threats (perhaps, however, in rapid succession).

An second consideration unites HPM and HEL: the problem that in Anglo-Saxon terms is called SWAP, that is Size Weight And Power (dimensions, weight and power).

We have noticed that in all the DEW prototypes examined so far the problem of the size of the weapon systems (ABL requires a 747!), As well as the problem of weights and that of the power available and transmissible on the target, are not adequately addressed. All problems that are certainly destined to be faced and mitigated over time (if the innovative development projects are appropriately financed, as it seems to be).

It is no coincidence that the only truly operating system, the LaWS, is embarked on board the ship (an environment in which the SWAP aspects are less restrictive).

An (easily imaginable) advance in SWAP aspects can bring DEWs to a level of competition with weapon systems currently employed, so many of the Cost / Benefit analyzes that currently still favor conventional weapon systems will likely be reversed. Provided, of course, to invest in development, especially in those critical technologies such as microwave generation or high-power laser emission devices.

A "technological leap" in these components would certainly change in a discontinuous way the importance of the DEW system affected by this leap.

An third consideration it relates to the weight and / or cost ratio between launcher and interceptor transposed to the DEW case. We start from the assumption that the competing solution of a DEW weapon system can be considered that consisting in a missile system. Of this generic missile system we take into consideration the launcher and the interceptor missiles that this launcher can launch and we assimilate these two subsystems to the microwave beam generation system and to the beam itself (we neglect in this comparison the discovery subsystems, essentially radar, and of fire control as roughly equivalent between a DEW and a missile system). If we consider the ratio between the weights (and / or between the costs) between the corresponding components of the two types of systems, we note that (see the following diagram):

  • the missile launcher, compared to the beam generation part of a DEW, is currently less heavy / expensive
  • the interceptor missile of a missile system will always be more expensive / heavier than a "shot" of a DEW system

And from this consideration derive a series of consequences that make a DEW system potentially preferable for:

  • Saturation attacks (drone swarms, low cost massive rocket attacks)
  • Attacks with low threat targets (it may not be worth using a missile, even at the cost of losing PK, probability to kill)

An fourth consideration is related to the performance of an HPM-DEW and HEL-DEW weapon system. This is the consideration that I consider most important and which incorporates many of the indications that have emerged from the previous analyzes.

Taking a look at the videos (those in the public domain are enough) on the fire tests of operational DEW weapons or under development certainly, from the point of view of performance, it is a bit to smile. Targets that move slowly and predictably (if not quite stationary), no evasion attempts, no countermeasures, considerable weapon exposure times.

Yet already today there are use cases for which DEW weapons seem to be preferable to more traditional competing systems (see the case of the US Navy's LaWS: "So far it has exceeded expectations", exceeded expectations, Admiral Bryant Fuller said2).

But, considering that it is reasonable to expect a rapid evolution regarding the SWAP (Size, Weight and Power) aspects, what can we foresee for the immediate future? Will a DEW system be preferable to "traditional" systems? And in which cases?

Here the discussion becomes much more interesting. Let's imagine a battle scenario of the future (not too far away, to tell the truth). Multi-domain operation (MDO; in addition to the traditional Air, Sea, land, it is necessary to add at least Space and Cyberspace), a dominant presence of systems unmanned (even in endowments to terrorist organizations or non-state militias, given that the technology is now within everyone's reach and that the changes to the objects available on the market are not so difficult to make), a multiplication of saturation attacks (see recent attack from Gaza to Israel and evidence that the excellent system Iron Dome however, it could not neutralize 100% of the threats, and it did so at a very high cost3. Above all, we are reminded of hypersonic threats, which are increasingly absorbing the budgets of all major global competitors.

It is precisely in these new scenarios that DEW systems are in perspective preferable to traditional systems, and in some scenarios even the only possible ones.

They will be preferable in all those cases in which the cost of the interception with traditional systems may be unsustainable or in any case difficult to justify. Let's think of a swarm of drones. Or a massive low-cost rocket attack.

Who will opt for missile interception once a DEW weapon has demonstrated a PK (Probability to Kill) above a certain threshold? And perhaps they may also be preferable in one of the new domains of possible battle, that of space. In Space, the advantage of DEW systems may be decisive in not depending on the weight and limitation of the number of interceptor missiles available, in addition to the fact that many drawbacks of the use of DEW systems in the atmosphere would be minimized or eliminated.

They will be irreplaceable for all those cases where the flight time of the kinetic weapon will make the neutralization of the critical threat.

One of the rules of thumb used to evaluate defense systems is that an interceptor must be at least 3 times faster than the target to be neutralized. Building an interceptor missile 3 times faster than a hypersonic weapon (which by definition moves at least at MACH 5) can be difficult if not impossible (just think that medium / long range ballistic missiles must be intercepted in the boost phase or during the mid-course precisely because otherwise, upon returning to the atmosphere, they would be too "fast").

With hypersonic targets a DEW system may be the only contrast solution.

Also read: "Direct Energy Weapons, DEW (part 1/3): introduction and classification"

Also read: "Direct Energy Weapons, DEW (part 2/3): laser and microwave weapon systems"

1 Active Denial System, ADS, https://en.wikipedia.org/wiki/Active_Denial_System

2 Laws declared operational, https://www.military.com/daily-news/2014/12/10/navy-declares-laser-weapo...

3 Lessons from Iron Dome, https://i-hls.com/wp-content/uploads/2013/07/Lessons-from-the-Iron-Dome.pdf

Photo: US Navy / author / web / DARPA

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