Atch A - FY10 JTO BAA Topics - Final - 15 June 09.doc

BROAD AGENCY ANNOUNCEMENT

HIGH ENERGY LASER - JOINT TECHNOLOGY OFFICE (HEL-JTO)

TECHNICAL TOPIC AREAS

Attachment A

Technical Topic Area 1: GAS LASERS

Point of Contact: Kevin Hewett, (505) 853-2684, e-mail: kevin.hewett@kirtland.af.mil Maximum award amount per task order NTE: $1M Technical period of performance may not exceed 12 months The objectives of this area are to research, develop and demonstrate technologies that lead to significant improvements in gas laser system power to weight ratio, increased system reliability and more logistically supportable operations.

GL-01: Advanced Engineering of Components.

Areas of particular interest include: (1) the structural engineering and chemical compatibility of composite materials for light weighting COIL Lasers; (2) the engineering required to economically produce the required chemicals for advanced fuels.

GL-02: Innovative COIL Components.

Research into new concepts for generators, nozzles, pressure recovery systems, etc. are desired. Hardware developed under this topic will be required to be compatible with a 300 mmol/s COIL. Detailed interface requirements will be provided upon contract award. A hardware deliverable is desired.

GL-03: Building a kW-class alkali laser.

Alkali lasers in the 100-W class have been demonstrated. A kW-class DPAL laboratory demonstration is desired. The DPAL systems proposed under this topic should be continuous wave (cw), diode pumped, and demonstrate efficient waste heat removal from the laser medium. Minimum run time for the laser at full power should be 30 seconds. Laser parameters which shall be measured at full laser power include output power, beam quality (report measurement technique), heat removed from the gain medium by the thermal management system, and optical-optical efficiency (both slope and threshold). Characterization of the temporal fluctuations in these parameters is desired.

GL-04: Physics based modeling of gas laser components.

Development of high fidelity physical models that can be used for virtual prototyping of gas laser components.

Technical Topic Area 2: FREE ELECTRON LASERS (FEL)

Point of Contact: Quentin Saulter, (703) 696-2594, e-mail: quentin.saulter@navy.mil Maximum award amount per task order NTE: $1M

Technical period of performance may not exceed 12 months Further scaling in the output power requires significant technology developments in several areas. Key developments are needed in the field of optical coatings with very low absorption, ability of the optical coatings to withstand harmonic loading in the UV, cooling of optical components, high peak and average current injector technology, superconducting energy recovery linac (ERL) structures that can stably accelerate electron beams and recover energy from electrons back into RF after FEL interaction. In this HEL-JTO BAA, proposals are sought that address the fundamental physics and engineering issues related to scaling the output power of the FEL up to and beyond the nominal megawatt range. HEL-JTO understands that many industries and laboratories would not be able to conduct most of the experiments at the beam parameters required for these efforts, but collaborative research with national laboratories may be needed to complete the proposed efforts.

Proposals are sought in three categories:

FEL-01: High average current injector technology

The objective of this effort is to develop FEL injector technology to deliver average currents of approximately 1 ampere with high bunch charge (≥1nC) and low emittance. Different groups have pursued several injector technologies over the past couple of decades. The most promising injector technologies to present involve photocathodes emitting electrons that are accelerated either in a dc field, an RF field at room temperature or an RF field in a superconducting cavity. To present, robust, long-lifetime (>weeks) photocathodes capable of operating at high average current (≥1Awith reasonable quantum efficiency ≥5%) using realistic drive laser power have not been fabricated or demonstrated. Photocathodes require expensive drive lasers with proper pulse format, power stability (to better than 1%) and a consistently reproducible spatial profile.

Other cathode technologies, namely thermionic, field emission and cathodes with diamond amplification have been proposed and need to be investigated. These and/or perhaps combinations of these must be developed, fabricated and demonstrated in the full scale injector field environment to meet robustness, long lifetime (≥weeks), average current (≥1A), quantum efficiency ≥5%) requirements for use in FEL.

Close coupling between theory, simulation and experiment in the development of FEL is important. Therefore, in addition to developing injector technology, detailed modeling and simulation of electron beam injectors is needed. These detailed models must include cathode emission, space charge and known RF effects. Any codes developed must be anchored to definitive experiments.

FEL-02: Investigation of methods to improve the electron beam stability at high average current levels, investigation and mitigation of beam halo, and investigation of Coherent Synchrotron Radiation and mitigation of its effects in increasing the beam emittance

To improve the overall electrical efficiency of the FEL, it has been recognized for some time that the best approach is to re-circulate the electron beam in the accelerator about 180 degrees out of phase with the accelerating bunches in order to recover energy not converted to photons. The stability of the electron beam in such an energy recovery linac is an important question that has not yet been investigated at average currents approaching one ampere that would be required for scaling the FEL to megawatt power levels. Both cumulative and regenerative beam break-up instabilities need to be investigated. Another serious issue is the part of the electron beam that strays off-course from the axis of the beam line forming a halo.

The high average current linacs cannot tolerate even one part in a million of the beam being lost hitting the walls of the beam pipe. At best, induced radioactivity in regions of the accelerator might make servicing difficult and require additional shielding. At worst, the accelerator/FEL might be seriously damaged or even destroyed. Mechanisms of halo generation need to be identified, understood and controlled. Shipboard FELs may contain transport sections that have tight bends. At high bunch charge and peak currents, coherent synchrotron radiation (CSR) would be emitted. The CSR is thought to increase the beam emittance and possibly to contribute to the formation of beam halo. At present this subject is not well understood. Both theoretical and experimental work is needed. All the above mentioned areas require well-anchored modeling codes as well as theoretical analyses that are supported by definitive experiments. Research in the area of RF drive power that would be required for the injector and the main accelerator and the coupling of the power to the RF cavities may also be addressed. Issues connected with the outcoupling of higher-modes generated in the cavities due to instabilities rightly belongs in this topic area.

FEL-03: Optical coatings, substrate cooling technology The objective of this effort is to develop optical coatings that have very low absorption in the fundamental wavelength as well as in the harmonics that are produced in any high power FEL. The absorption of the harmonics in the UV can lead to color center formations in the coatings. These are known to change the absorption characteristics at the fundamental wavelength. Since the FEL is expected to run for several minutes and possibly for several hours, the accumulated dosage of the optical flux due to the harmonics can become significant. The amplifier configurations may lower the flux loading on the mirror but not completely solve the potential problem of coating damage due to fundamental and harmonic loading. Another concern is the ability for the coatings and mirror to work over at least a narrow range of wavelength. A tunable FEL has certain advantages over a laser that operates at a fixed wavelength. The tunability of an FEL is seriously limited by the cavity optics in the case of oscillators and by the tunability of the seed laser in the case of an amplifier. The coatings and substrate technology developed under this proposal call should be generally applicable in the 1.0 to 2.4 micron range.

Technical Topic Area 3: ADVANCED CONCEPTS Point of Contact: LTC John Hartke, (845)938-8611, e-mail: john.hartke@usma.edu Maximum award amount per task order NTE: $500K/1st year, NTE $1M/2nd year Technical period of performance may not exceed 12 months AC-01: Optical Beam Combining

Proposals for this topic should address innovative and advanced concepts in optical beam combining that significantly exceed the performance features that have been reported up to now with such techniques as incoherent beam combining, polarization beam combining, wavelength beam combining, passive beam combing, etc. The approach may require innovation in the features of the individual lasers being combined in order to make the number of beams combined or properties of individual beams more tractable for HEL.

AC-02: New Approaches to Gain Media (Bulk, Fiber, Diodes etc)

Proposals for this topic should address innovative and advanced concepts in laser gain media such as composite and gradient ceramic structures, greatly improved quality of starting powders for ceramics, nano-grain ceramics, cryogenic gain media, single crystal or polycrystalline fibers, innovative fiber geometries, pioneering approaches to crystal growth rare earths doped into substantially improved thermally conductive host materials and geometries, and novel high-brightness diode lasers with emphasis on direct applicability to better pumping of specific HEL gain media, etc.

AC-03: Innovative Advances in Beam Phase Control Techniques

Proposals for this topic should address innovative and advanced concepts in beam phase-control devices for current challenges such as high-speed operation, high power handling capability, large dynamic range, nonlinear optical beam correction techniques, integrated beam control, utilization of MEMS technology for beam control, etc. Proposals should be quantitatively specific about the beam-control technology barrier being addressed and improvements to be sought in required beam control performance metrics.

AC-04: Emerging Femtosecond HEL Opportunities

Proposals for this topic should address innovative and advanced concepts in femtosecond-pulse-trains applications and describe beam characteristics and requirements to enhance the effects of target interactions, and HEL beam path characterization to achieve the applications. Atmospheric effects and target interaction on propagating femtosecond pulses are of interest. The proposal needs to effectively address improvements in femtosecond HEL system performance.

AC-05: Innovative Gas Laser Concepts Proposals for this topic should address innovative and advanced concepts of optically pumped gas lasers, pulsed chemical lasers, and other novel gas laser concepts. Proposals should be quantitatively specific about the gas laser technology barrier being addressed and improvement to be sought.

Technical Topic Area 4: SOLID STATE LASERS.

Point of Contact: Gary Wood, 301-394-0932, e-mail gwood@arl.army.mil

Maximum award amount per task order NTE: $1M Technical period of performance may not exceed 12 months

Proposals for this area should address enabling technologies for high average power solid state laser, SSL, (>100kW) engines with excellent beam quality (<1.5 x DL), short turn on times (<1s), long run times (>minutes) that could be fielded on military platforms for military applications. These types of lasers require research and development into a number of key technology areas such as optimized laser architectures, advanced laser components and integrated thermal management. Research and development into these areas should show scalability to high average power. Laser efficiency is a key element to the success of any solid state high energy laser engine. Efficiency allows for a more realizable SSL system by reducing: power lost to heat (wasted energy), thermal beam distortion (better beam quality), size & weight (more mobile), cost (affordable), and complexity (more rugged). All SSL research and development needs to make high efficiency, beam quality and scalability to high energy a prime consideration. Proposals of particular interest for the solid state laser area should address research and development in the following areas, not in priority order:

SSL-01 Eyesafer Laser Development

Proposals are sought that address development of enabling technologies for high power eyesafer lasers. These are lasers that have excellent atmospheric propagation and are longer than 1.5 micron wavelength so as not to effectively propagate to the eye retina. While still potentially dangerous as high power lasers the risk of collateral and accidental eye damage is reduced from scattered or unintended target designation. Non-single aperture approaches should show a path toward beam combining, either spectral or coherent, and concepts must show they have the potential to be fieldable (e.g. fiber concepts should be monolithic). Efficiency is an issue with these laser devices. Approaches should address efficiency and highlight areas that could lead to improvements.

SSL-02 Diode Laser Development:

Diode pump development for one micron (Nd, Yb) as well as eye-safer wavelengths (Er, Tm, Ho) is critical to the success of any high power solid state laser. Diode efficiency, brightness, availability and cost will determine how realizable a high power laser system can be as a DEW. The following types of development are sought for example: Improvements in diode thermal management; reliable and efficient operation at higher temperatures; reliable operation at cryogenic temperatures; high efficiency long wavelength (e.g. 14xx-15xx) diodes; high efficiency with high power and brightness; and narrow wavelength temperature stabilized diodes.

SSL-03 Fiber Laser Components:

All glass fiber lasers have an inherent ruggedness necessary for military field operations. This and the rapid advances in fiber laser scale up to high powers make this area attractive for proposals. In particular what is needed are fiber laser component developments. Such items as: pump couplers; beam combiners; optical isolators; novel LMA fiber development; photonic crystal fibers (which can demonstrate splicing with low loss at high power); improvements to the power handling capability, are all sought.

SSL-04 Ceramics Gain Media Development:

High quality (low scattering loss) laser ceramics have become the standard for high power slab lasers. They can be scaled up in size more readily than single crystals and are more homogeneous. In addition they have other attractive features such as the potential to gradient dope and the ability to introduce new laser hosts due to the lower processing temperatures of ceramics. Development of ceramic gain media is desired with a focus on achieving scattering losses comparable to the industry standard of Konoshima Inc. with a demonstratable ability to reproduce samples. Samples are to be delivered for government characterization with results made available within the government and to the vendor.

SSL-05 High efficiency, highly scalable power architectures:

Advanced diode pumped bulk solid state laser development with emphasis on very high efficiency (≥ 30% electrical to optical) and advanced thermal management in scalable architectures, such as for disk, slab lasers or others. Interested in demonstrations at or above 1 kW.

Technical Topic Area 5: BEAM CONTROL

Point of Contact: Richard Carreras, 505-846-2711, richard.carreras@kirtland.af.mil Maximum award amount per task order NTE: $1M

Technical period of performance may not exceed 12 months

The three beam control topic areas are identified with emphasis on hardware which can be delivered and tested in DEW Demonstration Platforms (i.e. NOP, DLWS, HEL TD, LAWS, THEL,…) using either a solid state or fiber HEL. In addition, technical topic area 6; “Beam Control Integrated Demonstration (BCID)” identifies the need for an integrated field demonstration to address specific beam control integration issues including the testing of developed HEL Beam Control components.

BC- 01: Beam Control Components

This area addresses the need to build Beam Control Components for testing in DEW (Directed Energy Weapons) Demonstration platforms with a total power of up to 150 KW from a Solid State Laser (SSL) with a 1.064 µm wavelength or a fiber-laser system operating at 1.075 µm. All developed components may be tested in the laboratory with final testing in a relevant field environment. The technology goals stated for the components are not necessary to be achieved, and some of the selections will be made by determining the most realistic and realizable designs. Developed components should be deliverable, standalone components with complete documentation and control software and be suitable for further government testing in a relevant field environment.

1) The development and availability of HEL Solid State Lasers have made it apparent that durable low-absorption, low-scatter HEL optics and HEL coatings technologies need attention. There is the need for further research and development to insure the survival of HEL components under exposure to HEL power in an operational beam control system. Ruggedized, durable optics/coatings are desired that can withstand total power of 150 kW with average irradiance levels of 100 kW/cm2 and localized irradiance spikes 3-times the average irradiance and survive 500 HEL exposures of 60-sec duration in an environment that has some contamination (clean, dry air environment). After 10-sec exposure to the HEL, the distortion of the HEL component should be less than 0.05 waves, rms, and have slope errors less than 0.05 waves per cm. The reflectivity/transmission of the coatings should be optimized for the HEL wavelength (1.064 or 1.075 µm), and provide good performance (reflectivity or transmission depending on the component) at an alignment wavelength (visible band) and TILL/BILL wavelength (1.3 to 2.1 µm). The proposed program should include consideration of alternative deposition processes and validation of coating designs through testing with an HEL, with quantitative coating metrology and characterization. Testing should also include an assessment of environmental effects on coating integrity. Also desired are methods for monitoring the “health” of HEL optical components to determine the status of components before a catastrophic failure occurs due to HEL heating. An In-situ monitoring system is highly desirable. All components developed under this topic will be deliverable to the Government for further government testing. For coatings, the components could be witness samples on a suitable substrate.

2) Advanced Wavefront Sensor (WFS) and Deformable Mirror (DM) components are desired to improve the performance of Adaptive Optics systems in HEL environments and to extend the operational envelope of future HEL SSL weapons systems. Performance considerations for these components are specified below. It is desired that all components which are developed be deliverable to the Government for further testing. The intent is for components developed under this topic to be integrated and tested in a relevant environment with candidate full-scale HEL demonstration systems.

Wavefront Sensor considerations: The wavefront sensor should operate in the 1.3 to 2.1 µm wavelength region and be able to accurately sense and reconstruct wavefronts from a beacon that has propagated through a turbulent atmosphere characterized by an r0 as small as 0.03 m and a Rytov number up to 1.0. The sensor frame rate along with data transfer and processing latencies should be able to support up to 50 kHz sample rates. The wavefront sensor should have at least 16 subapertures across the sensing diameter and sufficient pixels per subaperture to capture the uncompensated beacon and provide a closed-loop measurement precision of 0.01 waves per subaperture. The sensor should have high quantum efficiency (goal > 0.6) and low noise (goal < 20 noise electrons per subaperture per sample time). The sensor should be time gateable to permit range gating for background rejection.

Deformable Mirror Considerations: The deformable mirror should have at least 16 actively controlled actuators across the diameter and additional slave/guard actuators to provide smooth transition to edge of mirror. The mirror should have longer throw (dynamic range) than the standard 4 µm, in order to compensate for aero-optic as well as turbulence-induced wavefront distortions. The actuator speed should permit full-stroke correction up to 400 Hz and full correction for a turbulence PSD, resulting from propagation through an atmosphere with ro as small as 0.01 m and a Greenwood frequency up to 2.5 kHz. The mirror should be compatible with the application of a durable, low-absorption high-power coating. The coated mirror should meet the wavefront distortion requirements described under paragraph 1) above. In the mirror design, consideration should be to mirror alignment and to the effects of mirror incidence angle on the registration of the DM with the wavefront sensor.

3) Lightweight, durable and compact Illuminator lasers are desired. Illuminator lasers are critical components of all high energy laser weapon systems. They are used in conjunction with tracking sensors for precision tracking. Illuminator Lasers can also be used in conjunction with wavefront sensors to compensate for aero-optics distortions, atmospheric distortions, as well as wavefront errors in the weapon's optical system. Illuminator specifications include: narrow band output (spectral bandwidth and stability < 5 nm) in the 1.3 – 2.1 µm wavelength band (“eye-safe”), good atmospheric transmission), average power of 300 watts, selectable PRF from 5 to 50 kHz, and pulse-width of 15 ns or less. In addition the beam quality < 1.5 (defined by the bucket diameter containing 86% of far-field power, using, as the near-field reference, a Gaussian beam with same 86% diameter as the actual beam) is desired. It is desired that all components which are developed be deliverable to the Government for further testing.

BC- 02: Beam Control Algorithms

This area addresses the need to precisely maintain a HEL beam on a specific aim-point while the beam is subject to rapidly varying platform motion, atmospheric profiles, and target aspect and articulation changes. All algorithm implementations shall consist of high-speed, low-latency imaging and standard control interfaces, as well as software reconfigurable hardware. The goal would be a beam control development platform sufficiently flexible to accommodate rapid prototyping of a wide variety of algorithms and control techniques for high-speed image processing, dynamic tracking, aim-point maintenance, FSM control, and AO. All developed algorithms and/or components may be tested in the laboratory, with the final test being in a relevant field environment. Developed algorithms, computers and components should be deliverable, standalone subsystems with complete documentation and control software and be suitable for further government testing in a relevant field environment.

1) High bandwidth tracking and aim-point maintenance algorithms – the services are all considering highly dynamic engagements in their prospective HEL mission scenarios. These engagements often include active illumination of targets to obtain sufficient signal for precision tracking. Active illumination can produce image artifacts (scintillation and speckle) that degrade conventional track algorithm (centroid, correlation and edge algorithm) performance. Improved performance in track algorithms are sought to reduce the effects of target speckle and atmospheric scintillation, increase processing speeds (lower latencies), improve aimpoint estimation techniques (preferably not relying on a library of known threats), and provide higher frame rate operations using either 2-D or 3-D (LIDAR) image data. Bayesian tracking algorithms including the unscented Kalman filter and particle filter are also of interest for their functionality in systems with non-linear measurement and process models. Other techniques (using the extended Kalman filter) can result in large biases that are difficult to mitigate in HEL systems. Innovative methods to improve system boresight (fine track aimpoint to HEL hitspot, also called aimpoint bias) to less than 1 microradian are also desired.

2) Advanced tracking and aimpoint maintenance algorithms are usually designed with a combination of vector and floating point algorithms, and are implemented on general purpose CPUs. The resulting computer architectures are very complex and do not lend themselves to easy transportability from system to system. The investigation of algorithms for aimpoint maintenance and tracking that are implementable using fixed-point processing is desired. This is a challenging problem, especially because sub-microradian accuracy is often required for the beam pointing system. This type of accuracy is not easily achievable with current fixed-point processing.

BC- 03: Off-axis Beam Director Technology Challenges This call looks at addressing all critical issues that limit fabrication and practical use of an off axis beam director in an operational environment. Possible areas for research are: off axis system auto alignment architectures, structural and optical materials, simplified mechanical architectures having robust dynamics performance and structural survivability or other critical issues.

Technical Topic Area 6: Beam Control INTEGRATED Demonstration (BCID) Point of Contact: Richard Carreras, 505-846-2711, richard.carreras@kirtland.af.mil

Maximum award amount per task order NTE $1.5M

Technical period of performance may not exceed 12 months

White papers in this challenge should address an end-to-end demonstration of beam control system performance in tracking and adaptive optics correction.

Desired Demonstrations: The demonstration proposed must be performed in a field environment with a contractor selected beam director and beam control system. Demonstration of auto-alignment capabilities in the proposed system is a desired feature for the demonstrations. In addition, the demonstration must provide significant advances over currently demonstrated beam control system capabilities. These advances could include: 1) demonstration of 1 µr RMS tracking, atmospheric compensation, and aim-point selection and maintenance for a dynamic target in a Service mission scenario. 2) use of a high power laser to demonstrate high power beam control and target lethality for a Service mission scenario, , 3) demonstration of extended range (> 3 km) tracking and adaptive optics compensation 4) use and demonstration of state-of-the-art components and algorithms.

The mission scenario for the demonstration is at the discretion of the proposing contractor, but should have relevance to one of the Services’ interests. Possible scenarios include:

· Counter Rocket, Artillery, and Mortar (C-RAM)

· Counter Unmanned Aerial Vehicle (C-UAV)

· Precision Strike (Air to Ground)

The contractor may select, but must justify, the method of measuring performance. The contractor must also allow for an independent government furnished measurement of performance. Uncooperative targets will be used (no cooperative point sources at the target). We desire track and adaptive optics performance demonstrations against extended, relevant targets.

No government equipment, facilities, or targets can be assumed as government furnished equipment (GFE) without proof of agreement with the government authority responsible for the equipment/facility/targets. Points of contact for GFE are:

· Robert Kim, 505-853-7806, robert.kim@kirtland@af.mil

· Stan Patterson, (256) 876-4477, stan.patterson@us.army.mil

· Brian Hankla, (540) 653-2625, brian.hankla@navy.mil In addition, the contractor must specify any system component that will not be delivered to the government at the conclusion of the activity.

Performance: The selection criteria will be:

· Expected performance (estimated Strehl ratio achieved on target)

· Ability of components to operate at high power (~150 Kw @ 1.06 microns )

· System size and weight

· Soundness of design

· Effectiveness of the demonstration ( lethal demonstrations are desired but not required)

· System residual value (design modularity, design concept, technical risk)

Technical Topic Area 7: MODELING & SIMULATION (M&S)

Point of Contact: Bob Ackerman, (301) 342-8340, e-mail: robert.ackerman@navy.mil Maximum award amount per task order NTE: $220K/1st year, $200K/2nd year Technical period of performance may not exceed 12 months The use of Adaptive Optics techniques (AO) can improve the performance of High Energy Laser (HEL) systems in cases where there is significant optical turbulence. Normally this turbulence is represented in propagation simulations by the refractive index structure function (Cn2). Currently the DoD is developing the technology to implement AO techniques and it is likely that future HEL systems may employ these techniques.

In addition, in certain cases, the HEL beam may generate a distortion along the beam path due to the laser radiation heating of constituents of the propagation path. This effect is known as thermal blooming and is characterized by the thermal blooming distortion number Nd. Currently the DoD is developing HEL systems and technologies that have power densities sufficient to produce significant thermal blooming (Nd > 1). The use of AO to correct thermal blooming in addition to turbulence is a complex situation and is being actively investigated by DoD at present.

The HEL-JTO scaling law codes, High Energy Laser End to End Operational Simulation (HELEEOS) and High Energy laser Consolidated Modeling and Engagement System (HELCOMES) are in wide use within the HEL community to model the propagation of HEL beams as stand-alone simulations They are incorporated into higher level simulations in order to provide those simulations with the ability to simulate HELs. One of the main benefits of these scaling law codes is their acceptable level of accuracy in combination with fast (less than 1 second) computational time. For a number of simulation situations hundreds or even thousands of simulated engagements are conducted. In addition, high level simulations may simulate laser engagements along with many other kinetic and directed energy (DE) weapon systems.

One key limitation of the HEL-JTO scaling law codes is their limited ability to simulate the effects of AO compensation of thermal blooming. Presently, higher fidelity wave optics simulations such as Wavetrain and the Atmospheric Compensation Simulation (ACS), are required to model situations in which there is significant Cn2 and high Nd. These simulations provide the necessary accuracy, but are computationally intensive, and in many cases require hours to days to run when compared to fractions of a second required for the scaling law codes. This computational requirement limits the applicability of the higher fidelity simulations.

MS-01: Development of Candidate Scaling Laws for the Modeling of Adaptive Optics Compensation of Thermal Blooming.

This topic is seeking to develop a generalized set of candidate scaling laws for the problem of applying adaptive optics techniques to the correction of thermal blooming.

As Nd increases, the HEL beam shape initially tends to assume a crescent shape for a number of cases of interest. At still higher Nd, beam breakup occurs. It is recognized that these may represent different scaling law regimes. It is further recognized that the theoretical complexities may or may not allow a scaling law to be developed for the case of high Nd.

Proposals should result in proposed scaling laws suitable for incorporation in the existing HEL-JTO Scaling law codes HELEEOS and HELCOMES and should be applicable to overland and maritime, surface to surface, surface to air, air to surface, and air to air cases.

While it is highly desirable to have scaling laws for arbitrary levels of thermal blooming and turbulence, and for various adaptive optics systems including those with multiple deformable mirrors, it is recognized that available funding may not permit addressing all aspects of this problem. Proposals should at a minimum address adaptive optics compensation of thermally bloomed HEL beams for single mirror adaptive optics systems for the case of moderate thermal blooming where the beam is crescent shaped.

Proposals should address the scope of the proposed effort, range of conditions over which the proposed scaling law(s) are valid and the assumptions made of the underlying adaptive optics systems.

Using scaling law performance model techniques would allow the HEL-JTO sponsored scaling law codes to accurately simulate this important class of problems in a computationally fast manner.