Laser-Matter Interactions at SCARLET Science Center for Advanced

Laser-Matter Interactions at SCARLET Science Center for Advanced Research on Lasers & Engineered Targets Presented at the Fast Ignition Workshop 05 November 2006 Linn Van Woerkom The Ohio State University

Goal Develop techniques/protocols for the new generation of rep-rated Petwatt-class lasers Targets mass production & insertion Diagnostics Data management Thus enabling systematic studies of ultraintense laser-matter interactions With ultimate GOAL of providing test-bed infrastructure for developing point designs for Fast Igniton

We are NOT …. . building a big, bad laser …. .

Why Another Center? Currently there are many 20 – 200 TW lasers Many laser-matter processes studied Limitations due to low duty cycle – Need better statistics & reproducibility – Eventually need power plant Solution Build high rep rate petawatt lasers Problem What to do w/ rep-rated Petawatt laser? What about targets? – current targets ~$1 -5 k each at 1 Hz that hurts – Need mass production What about diagnostics – Currently film packs used for many diagnostics What about data collection? high data rates

The Team The Ohio State University – PI’s L. Van Woerkom & R. Freeman – Optics & diagnostics Dr. Enam Chowdhury – Facility & Integration John Marketon General Atomics – PI R. Stephens – Design Neil Alexander + others Targeting collaboration with CLF at RAL, UK

The Place Nuclear Physics Van de Graaff Facility • ~10, 000 ft 2 total • ~3000 ft 2 High bay • Lots of electrical • Renovations in initial design phase

The Place II

The New Place

The Plan Now parallel efforts – OSU purchases 20 TW system 20 fs, 400 m. J, 10 pps Ti: S commercial system – OSU renovates Van de Graaff building – OSU develops rep-rated diagnostics – OSU develops data management systems – GA designs & builds prototype target carrier Test at LLNL and/or others Work with target designers at RAL, UK Move into new facility July 2008 – Upgrade laser to 250 – 1000 TW

Need Systematic Studies Real Progress reproducible data rep-rated systems To explore efficiencies – Laser-electron front surface morphology – Laser-proton rear surface morphology To understand relativistic charge transport – Surface fields & resistivity – Transport in dense plasmas To develop diagnostic abilities – Transfer technology to large facilities On the road to a real point design …. .

Requirements 0. 1 – 1. 0 Petawatt Peak Power PRR 10 shots/hour scaleable to Hz level Two short pulse beams Automated target insertion & alignment Automated focus correction on each shot Reasonable contrast ratio Highly diagnosed laser record of each shot Modular architecture if $ stops we don’t

Concept Schematic 20 TW - Phase I Commercial System 200 TW – Phase II ~2009 1 -3 PW – Phase III (dreams are free) 20 fs, 400 m. J, 10 pps Ti: S Front End 20 fs, 4 J, 10 pps Ti: S amplifier 20 fs, 20 J, 1 pps Ti: S amplifier dia gn Rep-rated diagnostics os diagn tic ostic • Thermal loading issues • Need to load w/o amplifying • Feedback to adaptive optics • Scaleable to higher PRR c sti no iag d tic os diagn Rapid target insertion • target must align to diagnostics • laser must align to target Adaptive optics

Power & Energy Issues Must produce peak focused intensities in the range of Use ultrashort pulses 25 – 35 fs At 25 fs – 1 PW 25 J/pulse 40 -50 J before compression ~100 -200 J/pulse pump energy for Ti: S

Pulse Repetition Rate Issues Start “easy” minutes between shots – We need the time for target manipulation – Scale later to hertz-ish rates Solve problems along the way to higher PRR

Alignment Procedure Issues Diagnostics fixed point in space – How do we make it & find it? Align target to diagnostic center – How to align rep-rated targets? Align laser to target – straightforward using industrial technology? Maintain optimal focal properties – How do we move focus w/o destroying focus?

Target Insertion Issues Must handle 10 shots/hour & scale to faster Run several hours w/o venting target chamber Handle complex targets – – – Multilayers Cones Structures Must be economical!!? ? Align target to diagnostic center – Use industrial machine vision – Advanced image processing Protect subsequent targets – Radiation issues? – Debris issues

Target Fabrication

Metrology & SCARLET Positioner A transfer standard is passed between the systems A reference target (e. g. a rigidly mounted cube) is put in the Metrology Station – Its center and orientation are noted Fiducial cameras (orthogonal) METROLOGY STATION Fiducial cameras (orthogonal) SCARLET CHAMBER Target camera and lens (orthogonal) Hexapod: Alio Industries Target Fiducial lasers (orthogonal) Hexapod Positioner

The Hexapod High Vacuum Version Hexapod for Prototype Hexapods made by Alio industries

Target System Target Elevator Hexapod Optical table leg Attachment port for target magazine Vacuum chamber jacket around leg

Target Handling Target Manipulator shaft Target Elevator Target Alignment Tube and receptacle attach to hexapod here Hexapod Target Assemblies will get dropped of here (tube will surround hexapod, shown here offset

Alignment Issues Diagnostics bolt onto fixed chamber Must maximize solid-angle real estate Some diagnostics use collection optics – Ka & XUV – Can we move the collection optic and align to the target? What about laser pointing stability? – Must be “Titan-like” and then better know everything about everything on EVERY shot AT HIGH REP-RATE

Conclusions SCARLET at OSU laser-target facility – Look at rep-rated system issues Targets Diagnostics Data Management – Goal is to develop the infrastructure for rep-rated HEDP We have the building – Design in progress – Phase I – Target Insertions + 20 TW laser ~Summer ‘ 08 GA designing targets & carriers & metrology Technology transferred to other facilities