Laser-Matter Interactions at Laser-Matter Interactions at SCARLETSCARLET

Science Center for Advanced Research on Science Center for Advanced Research on

Lasers & Engineered TargetsLasers & Engineered Targets

Linn Van WoerkomLinn Van WoerkomThe Ohio State UniversityThe Ohio State University

Presented at the Fast Ignition Workshop05 November 200605 November 2006

GoalGoal

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 Thus enabling systematic studies of ultraintense laser-matter interactionsultraintense laser-matter interactions

With ultimate GOAL of providing test-bed With ultimate GOAL of providing test-bed infrastructure for developing point designs infrastructure for developing point designs for Fast Ignitonfor Fast Igniton

We are NOT …..We are NOT …..

building a big, bad laser …..building a big, bad laser …..

Why Another Center?Why Another Center?

Currently there are many 20 – 200 TW lasersCurrently there are many 20 – 200 TW lasersMany laser-matter processes studiedMany laser-matter processes studiedLimitations due to low duty cycleLimitations due to low duty cycle– Need better statistics & reproducibilityNeed better statistics & reproducibility– Eventually need power plantEventually need power plant

Solution Solution Build high rep rate petawatt lasers Build high rep rate petawatt lasersProblem Problem What to do w/ rep-rated Petawatt laser? What to do w/ rep-rated Petawatt laser? What about targets?What about targets?– current targets ~$1-5k each current targets ~$1-5k each at 1 Hz that hurts at 1 Hz that hurts– Need mass productionNeed mass production

What about diagnosticsWhat about diagnostics– Currently film packs used for many diagnosticsCurrently film packs used for many diagnostics

What about data collection? What about data collection? high data rates high data rates

The TeamThe Team

The Ohio State UniversityThe Ohio State University– PI’s PI’s L. Van Woerkom & R. Freeman L. Van Woerkom & R. Freeman– Optics & diagnostics Optics & diagnostics Dr. Enam Chowdhury Dr. Enam Chowdhury– Facility & Integration Facility & Integration John Marketon John Marketon

General AtomicsGeneral Atomics– PI PI R. Stephens R. Stephens– Design Design Neil Alexander + others Neil Alexander + others

Targeting collaboration with CLF at RAL, UKTargeting collaboration with CLF at RAL, UK

The PlaceThe Place

Nuclear Physics Van de Graaff FacilityNuclear Physics Van de Graaff Facility

• ~10,000 ft~10,000 ft22 total total• ~3000 ft~3000 ft22 High bay High bay• Lots of electricalLots of electrical• Renovations in initial Renovations in initial

design phasedesign phase

The Place IIThe Place II

The New PlaceThe New Place

The PlanThe Plan

Now Now parallel efforts parallel efforts– OSU purchases 20 TW systemOSU purchases 20 TW system

20 fs, 400 mJ, 10 pps Ti:S commercial system20 fs, 400 mJ, 10 pps Ti:S commercial system

– OSU renovates Van de Graaff buildingOSU renovates Van de Graaff building– OSU develops rep-rated diagnosticsOSU develops rep-rated diagnostics– OSU develops data management systemsOSU develops data management systems– GA designs & builds prototype target carrierGA designs & builds prototype target carrier

Test at LLNL and/or othersTest at LLNL and/or othersWork with target designers at RAL, UKWork with target designers at RAL, UK

Move into new facility July 2008Move into new facility July 2008– Upgrade laser to 250 – 1000 TWUpgrade laser to 250 – 1000 TW

Need Systematic StudiesNeed Systematic Studies

To explore efficienciesTo explore efficiencies– Laser-electron Laser-electron front surface morphology front surface morphology– Laser-proton Laser-proton rear surface morphology rear surface morphology

To understand relativistic charge transportTo understand relativistic charge transport– Surface fields & resistivitySurface fields & resistivity– Transport in dense plasmasTransport in dense plasmas

To develop diagnostic abilitiesTo develop diagnostic abilities– Transfer technology to large facilitiesTransfer technology to large facilities

On the road to a real point design …..

Real Progress reproducible data rep-rated systems

RequirementsRequirements

0.1 – 1.0 Petawatt Peak Power0.1 – 1.0 Petawatt Peak Power

PRR PRR 10 shots/hour scaleable to Hz level 10 shots/hour scaleable to Hz level

Two short pulse beamsTwo short pulse beams

Automated target insertion & alignmentAutomated target insertion & alignment

Automated focus correction on each shotAutomated focus correction on each shot

Reasonable contrast ratioReasonable contrast ratio

Highly diagnosed laser record of each shotHighly diagnosed laser record of each shot

Modular architecture Modular architecture if $ stops we don’t if $ stops we don’t

810 :1

Concept SchematicConcept Schematic

20 fs, 400 mJ, 10 pps Ti:S Front End

20 TW - Phase ICommercial System

20 fs, 4J, 10 pps Ti:S amplifier

200 TW – Phase II~2009

• Thermal loading issues• Need to load w/o amplifying• Feedback to adaptive optics• Scaleable to higher PRR

Adaptive optics

diagnosticdiagnosti

cdiagnostic

diagnostic

• target must align to diagnostics• laser must align to target

20 fs, 20J, 1 pps Ti:S amplifier

1-3 PW – Phase III(dreams are free)

Rapid target insertion

Rep-rateddiagnostics

Must produce peak focused intensities in the Must produce peak focused intensities in the range of range of

Use ultrashort pulses Use ultrashort pulses 25 – 35 fs 25 – 35 fs

At 25 fs At 25 fs – 1 PW 1 PW 25 J/pulse 25 J/pulse

40-50 J before compression40-50 J before compression

~100-200 J/pulse pump energy for Ti:S~100-200 J/pulse pump energy for Ti:S

Power & Energy IssuesPower & Energy Issues

19 21 210 10 /W cm

Pulse Repetition Rate IssuesPulse Repetition Rate Issues

Start “easy” Start “easy” minutes between shots minutes between shots– We need the time for target manipulationWe need the time for target manipulation– Scale later to hertz-ish ratesScale later to hertz-ish rates

Solve problems along the way to higher Solve problems along the way to higher PRRPRR

Alignment Procedure IssuesAlignment Procedure Issues

Diagnostics Diagnostics fixed point in space fixed point in space– How do we make it & find it?How do we make it & find it?

Align target to diagnostic centerAlign target to diagnostic center– How to align rep-rated targets?How to align rep-rated targets?

Align laser to targetAlign laser to target– straightforward using industrial technology?straightforward using industrial technology?

Maintain optimal focal propertiesMaintain optimal focal properties– How do we move focus w/o destroying focus?How do we move focus w/o destroying focus?

Target Insertion IssuesTarget Insertion Issues

Must handle 10 shots/hour & scale to fasterMust handle 10 shots/hour & scale to fasterRun several hours w/o venting target chamber Run several hours w/o venting target chamber Handle complex targetsHandle complex targets– MultilayersMultilayers– ConesCones– StructuresStructures

Must be economical!!??Must be economical!!??Align target to diagnostic centerAlign target to diagnostic center– Use industrial machine visionUse industrial machine vision– Advanced image processingAdvanced image processing

Protect subsequent targetsProtect subsequent targets– Radiation issues?Radiation issues?– Debris issuesDebris issues

Target FabricationTarget Fabrication

Metrology & SCARLET PositionerMetrology & SCARLET Positioner

A transfer standard is passed between the systemsA transfer standard is passed between the systemsA reference target (e.g. a rigidly mounted cube) is put in A reference target (e.g. a rigidly mounted cube) is put in the Metrology Stationthe Metrology Station– Its center and orientation are notedIts center and orientation are noted

Fiducial lasers (orthogonal)

Fiducial cameras (orthogonal)

Hexapod Positioner

Fiducial lasers (orthogonal)

Fiducial cameras (orthogonal)

Hexapod Positioner

Target

Target camera and lens (orthogonal)

SCARLET CHAMBERMETROLOGY STATION

Hexapod: Alio

Industries

The HexapodThe Hexapod

Hexapod for Prototype High Vacuum Version

Hexapods made by Alio industries

Target SystemTarget System

Attachment port for target magazine

Optical table legVacuum chamber jacket around leg

Target Elevator

Hexapod

Target HandlingTarget Handling

Target Elevator

Target Manipulator shaft

Hexapod

Target Alignment Tube and receptacle attach to hexapod here

Target Assemblies will get dropped of here(tube will surround hexapod, shown here offset

Alignment IssuesAlignment Issues

Diagnostics bolt onto fixed chamberDiagnostics bolt onto fixed chamber

Must maximize solid-angle real estateMust maximize solid-angle real estate

Some diagnostics use collection opticsSome diagnostics use collection optics– KK & XUV & XUV

– Can we move the collection optic and align to Can we move the collection optic and align to the target?the target?

What about laser pointing stability?What about laser pointing stability?– Must be “Titan-like” and then betterMust be “Titan-like” and then better

know everything about everything on EVERY shot AT HIGH REP-RATE

ConclusionsConclusions

SCARLET at OSU SCARLET at OSU laser-target facility laser-target facility– Look at rep-rated system issuesLook at rep-rated system issues

TargetsTargets

DiagnosticsDiagnostics

Data ManagementData Management

– Goal is to develop the infrastructure for rep-rated HEDPGoal is to develop the infrastructure for rep-rated HEDP

We have the buildingWe have the building– Design in progressDesign in progress– Phase I – Target Insertions + 20 TW laser ~Summer ‘08Phase I – Target Insertions + 20 TW laser ~Summer ‘08

GA designing targets & carriers & metrologyGA designing targets & carriers & metrology

Technology transferred to other facilitiesTechnology transferred to other facilities