Military

High Energy Laser Area Defense System (HELLADS)

The Air Force expected as of 2016 to have an operational laser small enough to be mounted on a plane by as early as 2020. That system, called the High-Energy Liquid Laser Area Defense System (HELLADS) was currently under construction, following a round of successful prototype tests by General Atomics, a military contractor.

The goal of DARPA's High Energy Liquid Laser Area Defense System (HELLADS) program is to develop a high-energy laser weapon system (~150 kW) with an order of magnitude reduction in weight compared to existing laser systems. With a weight goal of less than 5 kg/kW, approximately 750 kg, or 1650 lbs, an order of magnitude less than current laser weapon systems with similar power. This weight reduction enables tactical aircraft, such as fighters, bomber, tankers, and UAVs to carry the HELLADS. HELLADS will significantly increase engagement ranges compared to ground-based systems.

The goal of the HELLADS program is to develop a 150 kilowatt (kW) laser weapon system that is ten times smaller and lighter than current lasers of similar power, enabling integration onto tactical aircraft to defend against and defeat ground threats. With a volume of three cubic meters for the laser system, HELLADS seeks to enable high-energy lasers to be integrated onto tactical aircraft, significantly increasing engagement ranges compared to ground-based systems.

By combining the high energy delivery of solid state laser technology with the efficient thermal management of liquid laser technology, HELLADS has two main advantages over any HEL predecessors. One, the configuration is small and light enough to be carried on more tactical aircraft such as fighters. Two, the thermal management greatly increases HEL fire power by increasing dwell time on target.

This program initiative will investigate and validate a revolutionary laser design that enables a lightweight HEL weapon system. HELLADS will design, fabricate and test a prototype 15 kW sub-scale HEL system. A laboratory demonstration of key performance parameters will be performed, followed by the fabrication and testing of a subscale 15 kW HEL laser. Once key weapon system parameters have been demonstrated, a full-scale 150 kW HEL weapon system will be fabricated and demonstrated. Finally, the 150 kW HEL will be integrated into a surrogate aircraft and key performance parameters will be demonstrated.

General Atomics, under a contract with the Defense Advanced Research Projects Agency (DARPA), is developing an advanced, diode-pumped, lightweight laser system. This system offers the potential for compact, lightweight laser weapons systems suitable for deployment on a wide range of tactical systems.

HELLADS is a revolutionary high-energy laser (HEL) system concept that has the potential to reduce the weight of a HEL by an order of magnitude. The first phase of HELLADS focused upon critical experiments to validate the feasibility of the liquid laser. This phase was broken into two sub-phases - the first of which (Phase Ia) is a seedling to demonstrate critical laser parameters and the second of which (Phase Ib) demonstrated a subscale liquid laser.

General Atomics (GA) is a traditional defense supplier. As a result, the technology and industrial base was not broadened in this effort. Other benefits did accrue, however, from the use of an other transaction. The use of an other transaction (OT) rather than a traditional FAR contract was expected to save seven months in development time over the four year duration of the project. This savings in schedule arose from the developmental nature of the program. By eliminating the need for extensive formal contract documentation at every step of the program, rapid iteration between the government program manager and the GA principal investigator enabled quick decisions to be made as data becomes available from the various experiments within the project. In particular, once the data from the index matching tests was acquired, the OT enabled a decision to go forward on the next experiment within one week whereas a FAR contract would require a formal reporting and documentation step that would require at least six weeks. Since there were four critical experimental steps in phase one alone, the schedule savings added up rapidly. The effect of the OT on rapid communication and decision making between the contractor and the government was enhanced significantly due to the potentially classified nature of some of the work. Further, the flexibility an OT offers in determination of intellectual property rights is expected to encourage the participation of nontraditional defense contractors and vendors of commercial items and services in later phases.

After the liquid laser feasibility was demonstrated in the first phase, the government exercised an option to have the contractor design and construct a 100 kW proof of concept HEL and demonstrate its performance in a ground demonstration over a four-year period.

In 2004 the High-Energy, Liquid-Laser Area Defense System (HELLADS) program was in the third of five phases. This phase consisted of developing the technology necessary to demonstrate a subscale prototype laser system in the laboratory. This subscale demonstrator shall be constructed in the same geometry and operate with a fluence comparable to that of the final weapon system.

The fourth phase shall consist of a ground-based laser weapon system demonstrator with an approximate average power of 150 kW. The laser weapon system demonstrator constructed in this phase shall employ a design and materials which demonstrate the ability of the final weapon to achieve low specific weight (5 kg/kW) and a compact geometry suitable for deployment on tactical systems. The High Energy Liquid Laser Area Defence System (HELLADS) will weigh just 750 kilograms and fit into a space about the size of a large refrigerator.

The final phase consists of the engineering, fabrication, integration and demonstration of a complete HELLADS weapon system on a tactical platform. The Government shall specify the platform during Phase 4 of the HELLADS program.

In order to insure a smooth transition from the laboratory laser to a deployable weapon system, it is desired to have the System Integrator participate in various engineering aspects of the HELLADS system during the current laboratory phase. In addition, the successful bidder will be responsible for providing input to the design of the Phase 4 weapon system demonstrator and may be responsible for constructing various elements of the Phase 4 system. In Phase 5, the successful bidder will assist with the engineering fabrication and integration of the weapon system on the tactical platform. These responsibilities may include target acquisition and tracking, beam control, fire control, and integration of the various subsystems on the tactical platform.

In late 2004 General Atomics sought potential bidders to perform system engineering and systems integration studies for a lightweight, 150 kW tactical laser weapon system. Based on responses received under the Request for Information (RFI), a Request for Proposal may be distributed to qualified respondents for work beginning in early 2005. A detailed Statement of Work for system engineering support, system integration, and other efforts will be included in the Request for Proposal. The anticipated performance period was March 2005 to December 2009.

The Acquisition, tracking and pointing (ATP) system envisioned will include a radar/infrared based target acquisition system which cues a high resolution, laser illuminator based beacon/tracker. The target set of interest includes, but is not limited to: artillery, mortars, rockets, cruise missiles, surface to air missiles and air to air missiles.

Fire Control contains those elements of the system which serve as the interface between the ATP system and the Beam Control system. In this context, Fire Control is principally concerned with identification of the target, range determination, measurement of atmospheric distortion, generation of wavefront correction matrix, irradiance control to achieve the desired probability of kill and human-machine interface.

Beam Control refers to the entire optical train from the laser to the output aperture of the weapons system. The Beam Control system will contain the necessary optics to combine the illuminator and high power lasers into a common shared aperture, fast steering and deformable mirrors to correct for atmospheric pointing and distortion and a variety of diagnostics. The successful bidder will be responsible for the detailed design and integration of the Beam Control System. However, specific elements are being developed in parallel to the current phase of HELLADS. These elements include advanced laser illuminators and a lightweight beam director. It is expected that the Beam Control system will take advantage of these developments. Either General Atomics or the US Government may elect to contract for these elements independently and provide them to the contractor responsible for Beam Control.

The System Integrator may be required to work with General Atomics on the development of an integrated wavefront sensor/adaptive optics package. The overall objective of the system is to achieve high irradiance on target. This will require correction for atmospheric distortion and may require pre-correction within the laser resonator. It is envisioned that HELLADS will develop an integrated adaptive optics system which divides the principle distortions between an external cavity fast steering mirror, and adaptive optics which may be intra or extra-cavity to produce an optimized wavefront control package.

While the HELLADS laser can operate in both pulsed and continuous modes, it can be assumed that majority of engagements against the target class described previously will be continuous. The successful bidder will work closely with General Atomics and potentially other subcontractors to provide lethality estimates and analysis for the HELLADS weapons system.

General Atomics is responsible for the Laser, Thermal Management, Power and Control subsystems for the laser weapon as part of the system package. However, these subsystems must themselves be integrated with mechanical, power, heat transfer and control systems on-board the tactical platform. In addition, the Beam Control/Fire Control and ATP subsystems must be designed for integration on the tactical platform. In order to facilitate platform integration and interface control, it is desired to have the System Integrator participate in various system engineering aspects of the HELLADS system during the current laboratory phase.

The successful bidder will be responsible for providing input to the design of the Phase 4 demonstrator and may be responsible for constructing various elements of the demonstrator. In Phase 5, the successful bidder may have responsibility for the design and integration of the weapon system on the platform.

On 05 May 2005 Lockheed Martin announced that it had been selected by General Atomics as weapon system integrator for the High Energy Liquid Laser Area Defense System (HELLADS). As weapon system integrator, Lockheed Martin will support General Atomics in developing and demonstrating this innovative solid-state laser in a weapon system that is capable of being integrated on a range of potential platforms.

To support the HELLADS program, Lockheed Martin assembled a team led by its Space Systems Company, which partnered with two sister companies, Aeronautics and Missiles and Fire Control. SAIC is also a key member of the Lockheed Martin team.

In May 2015, HELLADS demonstrated sufficient laser power and beam quality to advance to a series of field tests. The achievement of government acceptance for field trials marked the end of the program’s laboratory development phase and the beginning of a new and challenging set of tests against rockets, mortars, vehicles and surrogate surface-to-air missiles at White Sands Missile Range, New Mexico. Integration of the HELLADS laser into a ground-based laser weapons system demonstrator began in July 2015 as an effort jointly funded by DARPA and the Air Force Research Laboratory. Following the field-testing phase, the goal is to make the system available to the military Services for further refinement, testing or transition to operational use. American defense contractor General Atomics was set to begin testing a 150-kilowatt-class laser in January 2016, and the firm hoped to see Air Force Special Operations Command (AFSOC) install the weapon on a gunship in the near future. Several other companies were developing laser weapons and "we're looking at all of them," Lieutenant General Bradley Heithold, head of AFSOC, said in an interview with Breaking Defense. "The technology is ripe for application on an AC-130."

General Atomics, which developed the MQ-1 Predator drone, also envisions equipping the company’s new jet-powered Predator C Avenger drone with a laser, derived from their High Energy Liquid Laser Area Defense System (HELLADS). Live-fire tests would be conducted at White Sands Missile Range, New Mexico, where the laser will be fired at a variety of airborne targets over the next 18 months.

The weapon produces a silent, invisible, but extremely hot beam by pumping electricity through rare earth minerals to excite their electrons and generate energy, Defense News reported. "The reason that I want it on an AC-130 is, right now, when an AC-130 starts firing kinetic weaponry, everybody knows you’re there," Heithold said. "What I want on the airplane is to be able to silently disable something."

Michael Perry, vice president in charge of the laser program at General Atomics, said providing the electrical power a laser needs aboard an aircraft and cooling the system are the chief integration challenges. But those hurdles are relatively minor compared to the feat of generating a laser able to burn holes in steel from miles away. "There's very little technical question that you can do this," Perry said of Heithold's goal. "The question is how much they want to do how quickly."

Liquid Laser

A liquid laser is a laser in which a liquid solution is the active species. The most common liquid laser media are inorganic dyes contained in glass vessels. They are pumped by intense flash lamps in a pulse mode or by a gas laser in the CW mode. Tunable dye lasers are a type for which frequency can be adjusted with the help of a prism inside the laser cavity.

Solid-state lasers have the disadvantage of occasional breakdown and damage at higher power levels because of the intense heat generated within the material and by the pumping lamp. The liquid laser is not susceptible to such damage; the crystalline or glassy rod is replaced by a transparent cell containing a suitable liquid, such as a solution of neodymium oxide.

Waste heat from the excitation process and absorption of laser radiation causes laser media to heat up and induces optical wavefront distortion, which in turn creates optical phase errors. One method to overcome this problem uses a system to derive an error signal from the optical phase errors. The error signal is fed back to the power supplies for the semiconductor diodes that excite the lasing liquid. This results in the introduction of an electrically controllable wedge into the optical cavity to correct the optical phase errors.

Lasers harness atoms to store and emit light in a coherent fashion. Stimulated emission, the underlying process for laser action, was first proposed by Albert Einstein in 1917. In 1960 the American physicist Theodore Maiman observed the first laser action in solid ruby. In 1966 a liquid laser was constructed by the American physicist Peter Sorokin. Working for the US Navy, Dr. Erhard Schimitscheck and chemist Rich Nehrich devised the first laser cavity that produced a visible beam by using a liquid laser material.



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