Alexei Yu. Kuznetsov1 , Vitali B. Prakapenka1, Andrew J. Campbell2, Thomas S. Duffy3, Guoyin Shen4, Dion L. Heinz1,

Mark L. Rivers1, Stephen R. Sutton1

1University of Chicago, Chicago, Illinois 60637, USA2University of Maryland, College Park, MD 20742

3Princeton University, Princeton, NJ 085444Carnegie Institution of Washington, 9700 South Cass Ave, Argonne, IL 60439

A New COA New CO22 Laser Heating System at Laser Heating System at

GSECARS: A COMPRES Infrastructure GSECARS: A COMPRES Infrastructure Development ProjectDevelopment Project

Acknowledge

GSECARS stuff:Mark RiversSteve SuttonYanbin WangVitali PrakapenkaPeter EngSanjit GhoseMatt NewvilleAtsushi KuboTakeyuki SanehiraNancy LazarzMike JaggerFred SopronClayton PullinsCharlie SmithPrzemek Dera

COMPRESCOMPRES

SynopsisSynopsis

1.1. IntroductionIntroduction - Current status of the project and further plans- Current status of the project and further plans - CO- CO22 laser heating: main goal laser heating: main goal

2.2. COCO22 laser heating system laser heating system- Key design considerations- Key design considerations

- Main characteristics- Main characteristics- Key problems- Key problems- Concept of the setup- Concept of the setup

3.3. Conclusion remarksConclusion remarks

Introduction Introduction

Current status of the projectCurrent status of the project 2007-2 installation of the CO2007-2 installation of the CO2 2 laser heating system in the ID-D stationlaser heating system in the ID-D station

Next stepsNext steps2007-32007-3 commissioning of the systemcommissioning of the system

2008-12008-1 commissioning with local proposalscommissioning with local proposals

2008-22008-2 open to general users open to general users

Introduction Introduction CO2 laser =10.6 m

YAG, YLF, Fiber lasers ~ 1 m

Laboratory Astrophysics Group of the AIU Jena: http://www.astro.uni-jena.de/Laboratory/OCDB/index.html

Jan L. C. Wijers, Technische Rundschau, Bern TR Transfer nr. 112 1996 F. Kemper et al. Nature 415 (2002), 295

COCO22 laser heating system laser heating system

Key design consideration

Integrated into existing NIR (~1 m wavelength) laser heating setup

Compact design

Power stability and control

Quick switch between the NIR and CO2 laser heating

IR (~10 m) sample alignment

Monitoring of the heating process (IR, Vis)

Full remote control and user friendly operation

Safety

COCO22 laser: main characteristics laser: main characteristics

Synrad f201 laser

Wavelength 10.2-10.7 m

Power output 200 W (CW), 250 W (PWM)

Mode quality TEM00, 98% purity

Polarization Linear, horizontal

Beam diameter 4.5 mm (at laser output)

Beam divergence 4.0 mrad

COCO22 laser heating system: key problems laser heating system: key problems

Power stability and power control

Pulsed width modulation command signal waveform

Polarizer-Analyzer-Attenuator (Brewster windows)

COCO22 laser heating system: key problems laser heating system: key problems

Sample alignment is a key issue in a successful HP experimentSample alignment is a key issue in a successful HP experiment

1. Chromatic effectProblems of using visible wavelength range:

2. Heating process is visible only when sample is starting to emit the light (T ~1500K)

Imaging in ~ 10 m

21

2> 1

COCO22 laser heating system: key problems laser heating system: key problems

Switch between NIR and CO2 laser heating

Silver based coatingReflects ~98% of the light at both wavelengths

COCO22 laser heating system laser heating system

General scheme

Beam splitter

What do IR images look like?What do IR images look like?

Magnified images of the wire

300 m

(a)

Back illuminated by IR light

(b)

300 m

Heated to 450 oC

Trade-off between magnification and image qualityTrade-off between magnification and image qualityDiffraction at 3 umMagnification 11

No Diffraction Raw ImageMagnification 11

Diffraction at 10.6 umMagnification 11

Diffraction at 10.6 umMagnification 4

Simulated by David Koren, II-VI Infrared.

What do IR images look like?What do IR images look like?

300 m

Sample in the DAC

Conclusion remarksConclusion remarks

The combination of a synchrotron X-ray source with a laser-heated DAC has been providing important results and new discoveries in high pressure mineral physics

Comprehensive laser heating setup is one of the important components defining versatility of high-pressure / high-temperature studies at GSECARS

Welcome to GSECARS Welcome to GSECARS Beamlines!Beamlines!

Temperature measurementsTemperature measurements

1

12),(

5

2

kT

hcB

e

hcTI

Planck’s law

Optics correction),(/),()( stBstst TITICorr

Emissivity correction),(),()(/),( TITCorrTI BEXP

)750()()(),( 750 TTT

0 500 1000 1500 2000 2500 3000

T=3500K

T=3000K

T=2500K

Spe

ctra

l rad

ianc

e

[nm]

T=2000K

Emissivity model

- fitting parametersTand750

- adjustable parameter)(T

Spot size of the focused laser beamSpot size of the focused laser beam

/#/#

f

DfK

ddd

FWHMFWHM

aberrationFWHM

ndiffractioFWHM

TotalFWHM

10 15 20 250

50

100

Total

SphericalAberrationS

po

t siz

e (

mic

ron

s)

Input beam diameter (mm)

Diffraction