XAPPER Capabilities, Progress & PlansXAPPER Capabilities, Progress & Plans

Presented by: Jeff Latkowski

XAPPER Team: Ryan Abbott,Brad Bell, and Keith Kanz

May 16, 2006

Work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under

Contract W-7405-Eng-48.

XAPPERXAPPER

JFL 05/16/06

Outline

Current capabilities

Progress since the ORNL HAPL meeting

Planned improvements

XAPPERXAPPER

JFL 05/16/06

Unexposed

Using our first high-quality ellipsoidalcondenser, pure tungsten can be damaged

9000 pulses @~1.5 J/cm2

Significant damage is observed at a fluence of ~1.5 J/cm2

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JFL 05/16/06

Tungsten test matrix: 10,000 shotson powder met.

1.2 J/cm2

~1.5 J/cm2

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Current capabilities

Soft x-ray source:Fluences of 0.25-1.25 J/cm2 ( ~ 10%)~50 ns 10-90% risetimeFWHM spot size is ~400 mRepetition rates ≤10 Hz106 pulses demonstrated, 105 pulse routine

Operational:Fluence measurement conducted using CCD (or CMOS)camera in conjunction with calorimeterVacuum typically ~10-4 torr, then inject xenon for pinchand come up to ~3 mtorrSamples actively heated up to 1000ºC (no active cooling)

Other diagnostics and analysis equipment:In-chamber sample imaging (low magnification)X-ray spectrometerPhotodiodes (fast and integrating)PIE: SEM, TEM, Veeco, x-ray radiography, optical microscopy

~1.0 J/cm2 needed to heat 600C sample to peak surface temperature of 2500C

XAPPERXAPPER

JFL 05/16/06

Since the ORNL HAPL meeting,we have finalized our pyrometer design

Wavelengths of 0.6, 0.8, 1.0, 1.2, 1.4 and 1.6 m selected

Using Avalanche Photodiodes (APDs):Si APDs at 0.6, 0.8 and 1.0 mInGaAs APDs at 1.2, 1.4 and 1.6 mEach will be integrated into an amplifier

Able to reuse SiO2 fiber and feedthrufrom UCSD thermometer

Pyrometer head design uses 3 optics(63, -40 and 63 mm focal length) andis 98.9mm long; 100 m field-of-view

1600 nm

1000nm

800 nm

600nm

500-1700nm

1400nm

1200nm

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Calibration will be a big partof our pyrometer effort

Emissivity is both wavelength and temperature dependent

Past work has assumed that (1) = (2)Okay assumption when operating at 0.7, 0.8 mNot a reasonable assumption for a wide range of wavelengths We would see ~2x variation in over our wavelengths of 0.6-1.6 mEmissivity ratios are notconstant with temperature

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Wavelength (m)

Em

iss

ivit

y

1340K

1380K

1430K

1610K

1830K

2040K

2140K

2640K

2650K

Data for polished single crystal tungsten.

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Calibration, (Cont'd.)

To enable calibration, we are procuring a high-temperature sample heater (2500C)

Measurements will be taken on the same sample with the pyrometer head sitting in the same orientation to the actual measurement (other than the direction of gravity)

Calibration measurementswill be taken every 100Cfrom 1500-2500C

Post-processing will be usedto determine temperature vs.time from the 6-channel data

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Calibration, (Cont'd.)

HeatWave, Inc. is building the sample furnace:Will mount to an 8” conflatWater-cooled flange5-mm-diameter portionof sample viewable at 45

(Very) hot test slatedfor end of June

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With the exception of the common opticsand minor items all parts are on order

Ordered:Sample furnaceBandpass filters (2 have arrived and exceed specifications)Longpass filters (to be used as dichroics)Si and InGaAs APDs

To be ordered soon:Optical breadboardOverall enclosureOptical mounts and tubesBK7/SiO2 lensesBatteries (for detectors)

To be fabricated:Light-tight enclosure for detectors (with filter mounts)Top & bottom plates for calibration chamber (in progress)

Arrived/Available:Signal cablingOscilloscopesOptical fiber & feedthru

We are on schedule for system assembly /

checkout in early-July

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Other progress and/or improvements

We have completed a forward model of the pyrometer system, including tungsten emission vs. and T, optical losses, and detector response

We have assembled a system to use as the calibration chamber

We are beginning to write procedures for the calibration furnace

Our safety paperwork is being updated

We are beginning to write the pyrometer data processing software

We have refined our CCD processing software (used to determine x-ray fluence) to account for path-dependent filter attenuation

Future exposure campaigns will include mass loss measurements (does this preclude us from putting multiple spots on a sample?)

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Summary

Since the last HAPL meeting, we have worked hard to design and procure the new pyrometer:

We expect to bring the pyrometer operational in July

We expect to have new sample exposures, with measured temperatures, in time for the next HAPL meeting

Planned sample priority is: (1) single crystal, (2) VPS tungsten, and (3) powder met. tungsten, (4) silicon carbide

We are holding off (for now) on the fabrication of a new ellipsoidal optic for use on XAPPER that would enable exposure of optical materials (low , big spot)

Right priority?

Back-up slidesBack-up slides

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JFL 05/16/06

The original thermometer has notworked for us for a variety of reasons

Original system used 200 m fiber with 75 and 40 mm lenses:

Gave a 375 m diameter field of view

XAPPER has a small spot size of~440 m diameter

Gave temperature variations in field of view (a definite no-no for optical pyrometry)

Switched optics to 62 and 150 mm lenses:

Field of view reduced to 83 m

Increased edge temperature to2450 ºC

Reduced field of view cuts signal by 20x, but 46% more solid-angle

Overall signal reduction of 14x

0.0

0.2

0.4

0.6

0.8

1.0

0 100 200 300 400 500

Spot radius (m)

Inte

nsi

ty (

a.u

.)

fieldof

view

Tpeak = 2500ºC

T83m = 2450ºC

T187m = 1510ºC

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Original thermometer, (Cont'd.)

Aligning the laser spot to the focused x-ray beam was impossible without manipulation under vacuum installed two-axis motorized gimbal system

Found a signal! Much celebration!

Movie shows field of view with old thermometer head

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Original thermometer, (Cont'd.)

We moved onto a new sample to start collecting real data signal was gone!

Discovered that the heavily damaged sample had been reflecting pinch light into the thermometer head

Confirming experiment: blocked EUV beam with a plate of glass and still saw same (visible light) signal

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Spectrum from the Astron

0

200

400

600

650 750 850 950 1050 1150

Wavelength (nm)

Inte

ns

ity

(a

.u.)

We have tried various fixes

Look for a dead-zone in the spectrum doesn't appear to be one

Temporal discrimination between pinch and emitted light pinch light persists too long

Vary angles not a real option (can’t get shallower angle; blackbody emission is lambertian, so signal would fall rapidly at steeper angles)

Look at the back side of a thin sample inadequate space

All of these options assume that we have a good signal that gets drowned out by reflected

pinch light. Instead, we see nothing until the material

damages. Suppressing the pinch light won’t fix the

underlying problem.

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Original thermometer, (Cont'd.)

3um_cold Front3um_cold Back3um_cold Front3um_cold Back

t (s)

T (

K)

10-9 10-7 10-5 10-3 10-1

3500

3000

2500

2000

1500

1000

Use thin sample (<5 m) to keep material hot for "long" time (milliseconds):

Sit at lower temperature, lose by T4 (12-18x)

Able to count for ~1ms instead of ~100ns, win big (104x)

Unfortunately, the ripples inherent to a thin foil are quite similar to those resulting from surface damage we immediately see reflected pinch light

XAPPERXAPPER

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Original thermometer, (Cont'd.)

Why doesn’t it work for us? Signal strength is just too low:

700/800nm aren’t the best wavelengths for our target temperatures; plus, small spread forces narrow bandpass (10 vs. 40nm) filters, further reducing the possible signal

Simple analysis shows that blackbody emission getting to thermometer head (with Lambertian distribution) is only 1400-2100 p/ns in each band

Emissivity probably ~0.3 and filters transmission is ~50%, so we have200-300 p/ns

Uncoated fiber ends (and possibly optics) result in further reductions

1.E+09

1.E+10

1.E+11

1.E+12

1.E+13

0 500 1000 1500 2000 2500 3000 3500 4000

Wavelength (nm)

Inte

ns

ity

(a

.u.)

600C

1000C

1500C

2000C

2500C

XAPPERXAPPER

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Source designed / built by PLEX LLC

Operates with xenon gas pinch to produce 80-150 eV x-rays

Operation possible at up to 10 Hz for millions of pulses

Condensingoptic

Materialsample

Plasmapinch

The XAPPER experiment is used to studydamage from rep-rated x-ray exposure