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JTO’s Perspective and Investment in High Energy Laser Systems

8 Nov 2004

LCDR Rich Nguyen

NAVY Rep, HEL JTO

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Outline

• JTO Organization • JTO Portfolio• JHPSSL• FEL• FY05 S&A Call for Papers• MRI

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ArmyRepresentative

ExecutiveAssistant

Budget/Finance

NavyRepresentative

Air ForceRepresentative

Tech Area,Contracts Monitor

Technology Council S&T Executives(Army,Navy, AF,

MDA, DARPA, DTRA)

Tech Area,Contracts Monitor

Tech Area,Contracts Monitor

MDADARPADTRA

USMC Reps

Technology Area Working Groups

Contractor Technical Support

DUSD(S&T)

Director, Joint Technology Office

JTO Programmatic Organization

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JTO Mission, Vision, and Objectives

• Mission: To lead DOD’s development of HEL weapon

technology

• Vision: Lasers will be a viable weapons in modern warfare

• Objectives: Make HELs Lightweight, Affordable, and

Supportable

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Fire Control

Wavefront Sensor

Dio

de

Pu

mp

Heat

HeatHeat

Dio

de P

um

p

Tar

get

Atmospheric Propagation - Thermal Blooming - Turbulence

Laser Device - Solid State - Chemical - Free Electron

- Advanced

Beam Control Lethality

Power Conditioning

Beam Conditioning& Adaptive Optics

Th

erm

al

Ma

na

ge

me

nt Beam

Combining

Example: Solid State Laser

Pointing

Illuminator

Laser-Target Interaction

Engagement Modeling

Windows &Mirrors

JTO Thrust Areas

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JTO Portfolio

• JTO maintains a portfolio of approx 80 Projects/Programs

• Addresses all thrust areas of HEL system

• Typical program size is $1M/yr

• Have larger programs in Electric Laser Initiative JHPSSL FEL

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JTO Investments(Larger Programs)

• JTO – 25KW JHPSSL $15M (FY03), $15M (FY04), $3.7M (FY05)

• AFRL – 25KW JHPSSL $10.2M (FY03/04)

• Army – 25KW JHPSSL $26M (FY03/04)

• JTO – 10KW Free Electron Laser $4M (FY03), $4M (FY04)

• Navy – 10 KW Free Electron Laser $14.1M (FY03/04)

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Joint High Power Solid State Laser Program (JHPSSL)

• Near Term Goal: Demonstration and Fabrication of a 25 kW Laser System with near diffraction limited beam quality and useful metrics

• Ultimate Goal: Demonstration of 100 kW Militarily Significant Laser System

Mission: to significantly accelerate development of solid state laser technology for future High Power Tactical Laser programs

 

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JHPSSL Technical Requirements

SOA: P=500W, BQ=1.1xDL, Eff<5%, <2W/kg

Parameter Development GoalsDesired Value

Output Power 25 kW > 100 kW

Beam Quality <1.5 xDL (goal: 1.2) 1.1 x DL

Run Time 300 s 300 s

Start-up Time 1 s (goal: 100 ms) 10 ms

Wall-Plug Efficiency > 10 % > 20%

Output Power-to-Mass 20 W/kg 50 W/kg

Beam Jitter 5 % 5 %

Temperature Range Operate: 5 to 35 °CStore: –29 to 49 °C

Operate: 5 to 35 °CStore: –29 to 49 °C

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JHPSSLProgram Plan

• 25 KW lab demonstrations is scheduled in Jan-Mar 2005 at all three facilities (LLNL, Raytheon, NGST)

Raytheon & NGST contracts are fully funded LLNL will need 1QFY05 funds from Army

• Gov’t team (MIT/LL, JTO, ARL, SMDC, & AFRL) perform BQ and power measurements at each facility, Mar 2005

• 100KW RFP plan in 3QFY05 (open competition); Tech Council decision for contract(s) award Sep 2005

BAA solicitation/ technical criteria set by joint team FY05 JTO funds available for kick-off effort

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FEL -- Surface Navy Threats Protection

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FELTactical System Goal

Top Level Power = 1 to 3 MW, controllable

down to 100 kW λ = 1 - 3 µm BQ < 2 times diffraction limit Duty Cycle = 30 seconds run time,

repeatable after 5 minutes

Injector & Accelerator ~ 0.5 Amp average current & ~ 0.5 nC/bunch per MW 2 °K Superconducting RF (500 - 750 MHz) linac 100 MeV Beam with Energy Recovery

Wiggler & Resonator Short Rayleigh length 1% - 2% Extraction efficiency wiggler Near concentric resonator

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MW-Class FELKey Technical Issues

• Photoinjectors with ~ 1 A average current, ~ 1 nC/bunch injector Development needed to achieve all requirements simultaneously Issues with photocathodes, drive lasers, and emittance control

• Anchored Models & Simulations Coherent synchrotron radiation (CSR) and other beam break-up effects degrade

the electron beam quality when focusing & bending Where are the limits? - More data & better models are required to manage effects

• Efficient wiggler & compact, survivable optical resonator High intracavity power & small beam stress conventional resonators & optics Need short Raleigh length wigglers, resonator concepts & improved optics/coatings

• Propagation efficiency of an intense FEL beam Effects of maritime and other tactical atmospheric paths not yet adequately

understood Effect of the FEL pulse format on beam propagation (degrade or enhance?)

• Optimum FEL concept for scale-up Trades required to balance the challenges faced by the evolving subsystem

requirements and competing approaches

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FELPhoto Injectors

• Three classes of potentially scalable Photo Injectors are being developed

All generate free electrons by striking a photocathode emitter with a pulsed laser beam All need robust, long life drive lasers and high QE photocathodes in visible

• DC guns (Jlab & AES) Accelerate the electron bunch using a DC electrostatic field (~500 kV) Inject 500 kV electrons into SRF cavity to accelerate to 5 – 10 MeV Have demonstrated continuous (hi rep-rate), low charge/bunch operation Challenge: large charge/bunch without space charge effects degrading emittance Most mature, probably leading candidate for 100 kW FEL

• RF guns (LANL & AES) Accelerate/control the electron bunch using RF fields & focusing magnets Uses normal conducting RF accelerators if are required Have demonstrated low rep-rate, high charge/bunch operation Challenge: thermal management of room temperature RF accelerator at high accelerator

gradient Less mature than DC gun, probably lowest risk for MW FEL

• SRF guns (BNL & AES) Accelerate the electron bunch using RF fields in SRF linac cavities Cryogenic photocathode Challenge: thermal management of cryogenic and superconducting portions of the injector

with high power drive laser beam and high average current Least mature but best fit to SRF FEL if technical challenges can be addressed

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FY05 S&A CallFEL

• FEL: 01) High Average Current Electron Gun and Injector Technology

• FEL: 02) Amplifier Technology Development

• FEL: 03) Technologies To Reduce FEL Construction Costs

• FEL: 04) Compact RF Sources

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FY05 S&A CallFEL: 01

• FEL: 01) High Average Current Electron Gun and Injector Technology

“ Proposals in this area should address technologies that support low-emittance consistent with 1 micron wavelength FELs and average currents approaching 1 ampere. Robust electron gun technology, e.g. employing photocathodes, is required that permits long term operation in realistic vacuum environments with a quantum efficiency leading to workable power requirements for the cathodes drive laser. Superconducting and normal conducting technologies are of interest.”

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Multi-Disciplinary Research Initiative Projects

• High Average Power Diode Pumped Solid State Lasers PM: John Zavada, Army Research Office Principal Investigator: Dr. Robert Byer, Stanford University

• Affordable High Energy Laser Systems PM: Arje Nachman, Air Force Office of Scientific Research Principal Investigator: Dr. Jerry Moloney, University of Arizona

• High Power, Closed-Cycle Chemical Lasers PM: Michael Berman, Air Force Office of Scientific Research Principal Investigator: Dr. William McDermott, Denver University

• High Power, Closed-Cycle Chemical Lasers PM: Michael Berman, Air Force Office of Scientific Research Principal Investigator: Dr. Wayne Solomon, University of Illinois Urbana-

Champaign

• Atmospheric Propagation & Compensation of HEL PM: Kent Miller, Air Force Office of Scientific Research Principal Investigator: Dr. Steve Gibson, University of California-Los Angeles

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Multi-Disciplinary Research Initiative Projects (Cont’d)

• High Power, Lightweight Optics PM: Charles Lee, Air Force Office of Scientific Research Principal Investigator: Dr. Hubert Martin, University of Arizona

• FEL -- High Quantum Efficiency Robust Dispenser Photocathodes PM: Quentin Saulter, Office of Naval Research Principal Investigator: : Dr. Patrick O'Shea, University of Maryland

Issues: Photocathodes are a weak link in FELs

Goal: High quantum efficiency, robust dispenser photocathode using green light or IR drive laserApproach: Theory and Experiment with a focus on dispenser photocathodes

• FEL -- Diagnostics & Control Methods PM: Quentin Saulter, Office of Naval Research Principal Investigator: Dr. Todd Smith, Stanford University

Issues: Need Better Phase Space Mapping techniques for High-Quality Beams Goal: Develop techniques for measuring high average current beams that are

suitable for interface with control system Approach: New schemes using: Optical Diffraction radiation, Optical pepper

pots, Optical synchrotron interferometry

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Questions?