Directed Energy Weapons: From War of the Worlds to the Modern Battlefield
“An almost noiseless and blinding flash of light … this invisible, inevitable sword of heat”: When H. G. Wells first wrote these words more than 100 years ago in his classic novel The War of the Worlds, they were not much more than the stuff of science fiction. However, with the significant developments in directed energy weapon (DEW) technology that have occurred in the century since that time, these “swords of heat” have clearly emerged from the pages of fiction to full-blown scientific reality.
Interestingly, the first working laser was described as a solution looking for a problem. But it didn’t take long for innovators to develop the laser’s unique ability to generate an intense narrow beam of light that could be harnessed for science, technology, medicine, and a wide range of other disciplines. And today, lasers are everywhere—from research laboratories to retail checkouts, medical clinics, communications networks, and now, advanced weapons.
The coherent optical oscillator first imagined by Theodore “Ted” Maiman of Hughes Research Laboratory (HRL) was called the maser (Microwave Amplification by Stimulated Emission of Radiation). Contemporary masers emitted electromagnetic (EM) waves across a broader band of the EM spectrum, so Charles Townes suggested using “molecular” to replace “microwave” to be more linguistically accurate.
Russian physicists described theoretical principles of the maser’s operation in 1952. Independent of Russian work, Townes and two associates built the first ammonia maser at Columbia University in 1953. Their device used stimulated emission in a stream of energized ammonia molecules to produce microwave amplification at a frequency near 24.0 GHz. Townes continued working to describe the principle of the “optical maser”—the laser (Light Amplification by Simulated Emission of Radiation)—after which Maiman created the first working laser model in 1960.
Maiman’s ruby laser design resulted after HRL provided company funds to continue work from a U.S. Army Signal Corps’ ruby maser redesign project. On May 16, 1960, Maiman demonstrated his ruby laser using a pulsed light source, lasting only a few milliseconds to excite the ruby. A short flash of light resulted, providing more power than previously imagined.
Lasers work by adding energy to atoms and molecules to create a high-energy—or excited—state. When excitation occurs, light waves pass through materials to stimulate more radiation. Maiman’s flash-lamp design emptied the ground (lowest-energy) state of the ruby, causing a stimulated emission to provide laser action.
Continued shortening of laser light pulses has increased instantaneous power to millions of watts. Lasers now have powers as high as 1015 (a million billion!) watts. Nonlinear interactions between light and matter double and triple the frequency of light to the point that an intense red laser can produce green light.
Most conventional weapons rely on explosives (chemical energy) for their destruction mechanism. They either explode on target (as bombs) or create kinetic energy (as bullets). Electric weapons use stored electrical energy to attack or destroy targets and generally fall into two categories: (1) DEWs, and (2) EM launchers. Electric weapon types are shown in Figure 2.
DEWs send energy, not matter, toward a target. DEW technologies typically take the form of high-energy lasers (HELs), charged-particle beams, and high-power microwaves (HPMs). EM launchers use electrical energy to throw a mass at a target, making them distinctly different from DEWs. EM launchers are rail guns, coil guns, or induction drivers, and all use strong magnetic fields to push against projectiles. Electric guns are electric weapons, but they are not DEWs.
Figure 1: Electric Weapon Types (NAVSEA Image).
DIRECTED ENERGY WEAPONS
The Department of Defense (DoD) has been investing in DEWs since the 1970s. HELs and HPMs have reached the point of operational test and evaluation readiness and, in some cases, battlefield operational use.
HEL weapon systems have been envisioned for many years. Early on, the Navy led development with creation of the world’s first megawatt-class, continuous-wave, Mid-Infrared Advanced Chemical Laser (MIRACL) at White Sands Missile Range (WSMR), NM. After testing, MIRACL ultimately engaged static and aerial targets for many years but eventually proved to be the wrong choice for the Navy’s (surface) self-defense mission. Its development did, however, lead to development of the Air Force’s Airborne Laser (ABL) and the Army’s Tactical High-Energy Laser (THEL). All three laser systems are chemical lasers that use toxic chemicals and operate in less than optimal wavelengths; thus, they are poor choices for most naval applications.
Solid-state lasers, including fiber lasers, are electric lasers that have moved to the forefront of the DoD’s research and development efforts for near-term HEL applications. Of particular interest to the Navy is the free-electron laser (FEL). The FELs speed-of-light delivery of HEL energy can defeat high-g maneuvers of newly developed foreign anti-ship cruise missiles (ASCMs).
High-Power Microwave Weapons
Like lasers, microwave weapons have been a fantasy ever since the invention of microwave power generators. In 1932, the British government recognized that German bombers could penetrate British air space and bomb civilian populations and infrastructures. In 1934, the British Air Ministry wanted a death ray that could kill enemy pilots and/or detonate bombs while still on enemy planes. A former meteorologist, who was also an expert on radio signals, suggested using energy reflected from aircraft. This technology is known as radar (Radio Detection And Ranging), and while it is not a DEW, its roots can be traced to the military’s desire for such capabilities.
HPMs—which are high-power radio-frequency (RF) systems—have progressively increased in power density, making it now feasible to integrate the technology into weapon systems. Initial applications suffered due to their inability to obtain militarily useful outcomes. Many feasible military applications including nonlethal, antipersonnel weapons, and nonkinetic anti-materiel weapons have surfaced over recent years. These concepts offer unique warfighter capabilities but are difficult to achieve.
Overcoming HPM propagation losses has driven some concepts into platforms such as unmanned aerial vehicles (UAVs) or cruise missiles to deliver the HPM device to a target for close-in engagement. Field-testable prototypes have been developed to demonstrate operational utility of these concepts. In some cases, the prototypes have been, or will be, deployed operationally to support troops in theater.
21ST CENTURY TECHNOLOGIES
In January 2008, the Office of Naval Research (ONR) successfully conducted a record-setting firing of an electromagnetic rail gun (EMRG) at the Naval Surface Warfare Center (NSWC) in Dahlgren, VA (see Figure 3). The event took place in front of an invited audience, including then-Chief of Naval Operations (CNO) Admiral Gary Roughead, who said, “We should always be looking for the next big thing, to make our capability better and more effective than anything else on the battlefield.” He also said, “I never, ever want to see a sailor or marine in a fair fight. I always want them to have the advantage.”
Figure 3: High-Speed Photo of Record-Setting Firing of NSWC Dahlgren’s EMRG (U.S. Navy Photo).
The Navy’s first rail gun program was initiated in 2003. It facilitated a key partnership between leading scientists and engineers from industry, military, and government labs. The Phase I goal of conducting a proof-of-concept demonstration at 32 MJ of muzzle energy was achieved. Future weapon systems at full capability could fire a projectile more than 200 nautical miles, in contrast to the Navy’s MK45 5-inch gun, which has a range of approximately 13 miles.
The EMRG uses high-power electromagnetic energy instead of explosive chemical propellants. Electricity generated by a ship is stored over several seconds in a pulsed power system. Next, an electric pulse is sent to the rail gun to create an electromagnetic force accelerating a projectile up to Mach 6. The kinetic energy warhead uses its extreme speed to propel a projectile farther and faster than any preceding gun.
The EMRG will give U.S. sailors a multi-mission capability, allowing them to conduct precise naval surface fire support or land strikes; ship defense; and surface warfare to deter enemy vessels. High-velocity projectiles will destroy targets as a result of kinetic energy rather than using conventional explosives, thus eliminating the hazards of high explosives on ships and unexploded ordnance on the battlefield.
Hypervelocity Projectiles (HVP) are next-generation, common, low-drag, guided projectiles that are capable of completing multiple missions from different gun systems (i.e., 5-inch, 155-mm, and future rail guns). They are configurable for various mission roles and gun systems through use of multiple Integrated Launch Package (ILP) components coupled with a modular, common airframe. With its increased velocity, precision, and extended range, the HVP will provide the capability to address a variety of current and future naval threats in the mission areas of naval surface fire support, ship defense, and anti-surface warfare using current and future gun systems.
Mission types will, of course, depend on the gun system and platform. Addressing mission requirements in the areas of naval surface fire support, cruise missile defense, and anti-surface warfare are some of the program’s top goals. Likewise, mission performance will vary from gun system, launcher, and ship. The HVP’s low-drag, aerodynamic design enables high-velocity, maneuverability, and decreased time to target. Coupling these attributes with accurate guidance electronics will provide low-cost mission effectiveness against current threats and the ability to adapt to future air and surface threats. Further, the HVP’s high-velocity, compact design eliminates the need for a rocket motor to extend the gun range. Being able to fire smaller, more accurate rounds will reduce collateral damage and provide deeper magazine potential and improved shipboard safety. And responsive, wide area coverage can be achieved from conventional gun systems and future rail gun systems. Finally, the HVP’s modular design can be configured to multiple gun systems to address different missions.
Additionally, ONR’s fiber laser-based system, LaWs (Laser Weapons System) (shown in Figure 4), can be retrofitted to augment capabilities of currently deployed surface combatant systems. Performance tests aboard the USS Ponce in 2014 resulted in hitting targets on top of speeding oncoming boats; destroying multiple moving, water-submersed targets; and shooting down a UAV. And all of these actions were accomplished almost instantaneously.
Figure 4: ONR’s Laser Weapon System (LaWs) (NAVSEA Photo).
Since its depiction in science fiction cartoons a century ago, DEW technology has grown into a viable, effective, and promising solution for a wide variety of current and future applications. And that may soon include the battlefield.
ONR has demonstrated that laser weapons are now both powerful and affordable. Supported by NSWC Dahlgren, ONR’s Laser Weapons System successfully tracked, engaged, and destroyed a threat representative UAV while in flight at San Nicholas Island, CA. This marked the first Detect-Thru-Engage laser shoot-down with a total of two UAV targets engaged and destroyed.
HVPs will also provide lethality and performance enhancements to current and future gun systems, allowing for future technology growth while reducing development, production, and total ownership costs.
Finally, getting the United States off gunpowder—which is one of Admiral Jonathan Greenert’s primary objectives for the future Navy and Marine Corps—is also nearing reality. LaWs and EMRGs are sure to be vital to future forces with their virtually unlimited magazines, constrained only by a vessel’s onboard power and cooling capabilities. And because a vessel’s biggest vulnerability is its explosive-filled magazine, these technologies will also make U.S. sailors and marines safer by reducing dependency on gunpowder-based munitions.
Perhaps Admiral Roughead’s “no-fair-fight” wish is closer than even H. G. Wells could have imagined.
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