Megawatt Laser Test Brings Space
Based Lasers One Step Closer
Source: Space Daily April 26, 2000
Redondo Beach - In a demonstration of the rising
maturity of high-energy lasers, TRW has conducted a test of the Alpha
high-energy laser that produced a 25 percent increase in the laser's
output power and improved its quality.
The successful, six-second test of the megawatt-class
Alpha was performed March 28 at TRW's Capistrano Test Site in Southern
California as part of the Alpha Laser Optimization (ALO) program. ALO
is funded jointly by the Air Force and Ballistic Missile Defense
Organization (BMDO).
The test marked not only the 22nd successful firing of
the TRW-built Alpha, but also a significant step forward in the
nation's disciplined maturation of the technology required to design
and deploy the Space-Based Laser Integrated Flight Experiment (SBL
IFX), an experimental, space-based missile defense system being
developed by the Air Force.
"The data gathered during this test of laser performance
and beam uniformity is a critical part of the process we're using to
develop and validate next-generation laser design tools," explained
Dan Wildt, TRW's SBL IFX program manager.
"The more we understand about Alpha's performance under
a variety of operating conditions, the better we'll be able to design
and produce a laser optimized for the size, weight and performance
requirements of the SBL IFX."
Like Alpha, the SBL IFX laser will be a cylindrical,
hydrogen-fluoride chemical laser, but will take advantage of
engineering advances in laser hardware since Alpha was designed in the
mid-1980s, he added. TRW is part of Team SBL IFX, a joint venture
comprising TRW, Lockheed Martin and Boeing that's designing and
developing the SBL IFX for the Air Force and BMDO.
According to Dan Novoseller, TRW's ALO program manager,
the purpose of the recent test was to increase the amount of power
extracted from Alpha's laser cavity by the optical systems that focus
the energy into a laser beam.
"Historically, as part of a conservative optical design
strategy, we've used hardware called 'clippers' to restrict the size
of Alpha's cylindrical, donut-shaped lasing cavity," he explained.
"Any photons that struck on or outside the clippers were
diverted to energy 'dumps,' which reduced the number of photons
available to form the laser output beam. Needless to say, we were not
getting a full measure of Alpha's potential beam uniformity or output
power."
In the recent test, he added, the clippers were
retracted to a position that did not prevent any photons produced by
Alpha from striking the optical systems that generate its output beam.
The results were significantly improved from all previous Alpha tests.
"In addition to producing about 25 percent more power
than previous tests, Alpha generated an output beam that was almost
perfectly round and more uniform in energy density," said Novoseller.
"These results raise our confidence in using a
cylindrical laser approach for SBL IFX and may help identify some ways
we can reduce the size and weight of SBL IFX subsystems required to
operate the laser."
As an example, Novoseller said improvements in laser
beam quality and output power produced per unit of chemical fuel would
allow Team SBL IFX to reduce the size and weight of the SBL IFX
laser's chemical fuel tanks without sacrificing any mission
capability.
The SBL IFX team plans to conduct additional testing of
Alpha later this year to gather additional understanding of how
changes in the chemical flow rate will affect its overall performance.
TRW has been engaged in laser research and development
since 1961. The company produces solid-state lasers for defense and
industrial applications and designs and develops a variety of
high-energy chemical lasers for space, ground and airborne
applications.
http://www.spacedaily.com/news/laser-00e.html