22 Feb 2011
FY2012 budget requests from the US Department of Defense include substantial funding increases for free-electron and liquid lasers.
Various types of high-energy laser and directed energy technologies have been earmarked for increased funding in the fiscal year 2012 budget requests presented by the US Navy, US Air Force and the Defense Advanced Research Projects Agency (DARPA).
Although the budget requests will be subject to intense debate within the US political system over the coming months, it is clear that these technologies are seen as a key part of future US defense operations.
The project that is attracting the largest funding in this area appears to be the Navy’s directed energy program, which largely relates to the development of a free electron laser (FEL) prototype. The FEL is still in the early stages of development, and is not expected to be used on a ship for at least a decade, but the Navy is budgeting for a sharp increase in spending under its directed energy program – more than doubling from $28.9 million in FY 2010 to $60.4 million in FY 2012.
“[The] increase in funding is primarily due to the start of the second contractual phase of the FEL innovative naval prototype (INP) program,” wrote the Navy in its request document. “A single contractor was awarded the contract in late FY 2010, and in FY 2011 the selected contractor will begin the critical design, development and installation portion of the FEL INP 100 kW test and demonstration program.”
That contractor is Boeing, which was awarded $23.7 million by the Office of Naval Research in September 2010 to demonstrate the FEL’s scalability by the end of calendar 2011. The funding increase will also support the development of compact, high-performance optics for the FEL prototype, including mirrors and an oscillator system.
Ultimately, the goal is to create a compact, megawatt-class FEL that could be used on board vessels to defend attacks from what the Navy describes as “high-maneuvarability cruise missiles and asymmetric threats”.
The technical challenges of achieving that in a military environment are huge – free-electron lasers rely on a beam of electrons, accelerated near to light speed, acting as the lasing medium. The beam travels through a magnetic field, producing a very widely tunable laser. And although recent reports suggest that achieving the 100 kW interim goal and scaling to megawatts is feasible in a laboratory environment, the energy demands of such a laser and the practical realities of operating an electron accelerator on board a ship will present many difficulties.
It isn’t just the Navy that is funding FEL development for defense. Under the Air Force’s high-energy laser (HEL) research activity, which funds early-stage work on many types of laser, the FY 2012 budget request calls for $4.3 million to scale FELs to 100 kW.
Overall, the Air Force HEL research program is aiming for a small increase in total funding to $54.1 million in FY 2012. It includes seven “major thrusts”, of which the FEL is one. Other thrusts within HEL include solid-state laser development, which includes the robust electric laser initiative (RELI) and calls for $12.8 million funding in 2012. The Air Force HEL program is also looking at scaling electrically pumped alkali lasers ($9.7 million in FY 2012, up from $6.9 million in FY 2010).
Meanwhile DARPA is aiming for a major increase in support for its high-energy liquid laser area defense system (HELLADS) program to develop a 150 kW weapon that is much lighter than current lasers that are able to produce such power. The HELLADS program received $19 million in FY 2010, which DARPA is planning to increase to $29.5 million for FY 2012.
According to the Pentagon agency’s FY 2012 budget request, a prototype unit cell laser module developed under HELLADS has shown an output exceeding 34 kW, and the next steps will include demonstrating a multi-module laboratory system delivering 150 kW. In 2012, the plan is to integrate the 150 kW laser with a ground-based demonstrator weapons system and to begin tests.
In addition to that, DARPA is grouping three projects relating to high-power lasers under a single program that it calls “Excalibur”. The individual projects include the high-power efficient and reliable laser bars (HiPER), revolution in fiber lasers (RIFL) and the coherently combined high-power single-mode emitters (COCHISE) activities. Combined funding for those projects will increase from $18.4 million in FY 2010 to $21.2 million in FY 2012 under DARPA’s proposals.
Near-term technical aims under Excalibur include a 3 kW fiber amplifier operating at more than 30% efficiency and with a near diffraction-limited beam, as well as a compact 500 W coherent array of single-mode laser diodes.
Table of contents photo credit: Raytheon