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Advances in Si-GDP, Ge-GDP and Glass

Capsule Fabrication

M.L. Hoppe,1 M.E. Schoff,1 N.G. Rice,1 A.L. Greenwood,1 A.A. Tambazidis,1

S.O. Kucheyev2

1General Atomics, P.O. Box 85608, San Diego, California 92186-56082Lawrence Livermore National Laboratory, P.O. Box 808,

Livermore, California 94550

22nd Target Fabrication Meeting

Las Vegas, Nevada

March 12-16, 2017

This work performed under the auspices of the U.S. Department of Energy by General Atomics under Contract

DE-NA0001808 and by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and

General Atomics IR&D Funds

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1) Partially densified glass capsules from silicon doped

glow discharge polymer (Si-GDP) for use in Pushered

Single Shell (PSS) experiments

2) Fully deuterated germanium doped (Ge-GDP)

capsules - also for PSS experiments

3) Improved route to manufacture glass capsule fill tube

assemblies (CFTA’s) using the Si-GDP -> glass process

4) Method for manufacturing machined “keyhole”

GDP/Si-GDP dual layer capsules for shock-timing

experiments

5) Latest progress in expanding the range of glass

capsules that can be made via the Si-GDP process

Recent development efforts to be discussed

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1998 Drop Towe r

2005 Si -GDP

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Partially converted glass capsules with significant D

enrichment for Single Pusher Experiments

Si-doped

GDP

Pyrolyze

in N

2

Sinter

in He/O2

1

2

PAMS Si-GDP/PAMS Si-GDP SiO2

2 3

Shrinks ~35%

Plan was to start from the Si-GDP to Glass Conversion process

Phase I: Using normal dopants (TMS and T2B) show process will work

Phase II: Replace TMS with DTMS and T2B with DT2B in GDP process

Phase 1 Results: @ 490ºC

Final Density 1.80g/cc

Silicon Density 0.66g/cc

OD ~1200mm; 11mm wall

SIMS shows there was

Hydrogen present but

cannot say quantitatively

how much

1200 mmTMS = tetramethyl silane

T2B = trans 2-butene

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Decision: IR shows Deuterium lost during glass

conversion

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01,0002,0003,0004,0005,000

IR Spectra

Si-GDP (no D) (TMS; T2B; H2)

Si-GDP (with D) (TMS;

DT2B; D2)

Wavenumber (cm-1)

Project stopped/put on hold until further notice

Wavenumber (cm-1)

Partially converted Glass from Si-GDP (no D)Partially converted Glass from Si-GDP (with D)

C-H

C-D

O-H

O-H

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Wavenumber (cm-1) Wavenumber (cm-1)

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Pre-glass conversion

Partial glass

conversion

Potentially of interest??

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Deuterated Ge-doped GDP capsules

fabricated for Single Pusher Experiments

on NIFPhase 1) Replaced precursor gases H2 with D2; T2B with

DT2B but keep normal tetramethyl germane (TMG)

- Refine coating parameters using normal TMG first to

minimize cost

IR Spectra:

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65011501650215026503150365041504650

C-H

C-D

Post PAMS pyro

1400 mm

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Phase 2) Replaced final precursor gas Tetramethyl

Germane (TMG) with deuterated TMG

IR Spectra:

C-D

IR spectra of Phase II D-GeGDP layer is

consistent with very high D enrichment

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6501,1501,6502,1502,6503,1503,6504,1504,650

Fully Deuterated GeGDP

(3.7mm) on PAMS mandrel

(12.5mm)

C-D

C-H (PAMS)

(PAMS background removed)

4500 3500 2500 1500 (cm-1)

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3He NRA for deuterium profiling

D(3He,4He)H1

3He + D = 4He + 1H

Q = 18.4 MeV

Quantitative Deuterium content can be measured

by Nuclear Reaction Analysis (NRA) with 3He beams

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Channel

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Norm

ali

zed

Yie

ld

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Energy (MeV)

CD (DPS-5)

SiCO Ge

C(He3,He3)C

diagnosticspulser

D(He3,He4)H

D(He3,H)He4

g7387.rbs

Simulated

Channel1,5501,5001,4501,4001,3501,3001,2501,2001,1501,1001,0501,000950900850800750700650600550500450400350300250200150100500

Co

un

ts

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Energy [keV]

D(He3,He4)H

D(He3,H)He4

Best NRA estimate

indicates ~65% D

enrichment for

DGeGDP sample but

error bar is still large

Problems to address in upcoming

NRA experiments

• Beam-induced D/H loss

• Noisy signal

• Shells -> Geometrical effects

Method calibrated using

Deuterated polystyrene

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Initial CFTA capsule drilling trials with Drop-Tower (DT)

glass capsules had limited success

Issues with DT

Glass

• Poor coupling of laser with

Glass capsule

• Irregular

shaped holes

• Micro-cracks

common

around holeDrop-tower Glass

Capsule with laser hole

Micro-cracks can lead

to failure at pressure50 mm

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Capsules starting from Si-GDP overcame the issues

encountered with Drop-Tower glass

Laser hole drilled in Si-GDP mandrel prior to

conversion to glass

• Laser coupling with Si-GDP much better than DT Glass

• Much more uniform and round hole shapes

• No micro-cracks around hole

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Machined Si-GDP/GDP capsules developed for

Keyhole Shock-timing experiments

Goal: Produce capsules consisting of GDP/ Si-GDP that

can be machined without cracking or deformation

4 Methods Considered:

1) PAMS pyro followed by machining

2) Machining followed by PAMS pyro

3) Machining follow by removal of PAMS using Toluene

4) Laser Drill small hole, short PAMS pyro, then

machining

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Substantial Issues with first three methods

1) PAMS pyro followed by machining

- Hairline cracks in Si-GDP layer. No

machining attempted. Likely due to

shrinkage difference between Si-GDP

and GDP during PAMS pyro

2) Machining followed by PAMS pyro

- resulted in severely distorted capsule

3) Machining followed by PAMS removal

using Toluene- Shells very fragile and difficult to process

1 mm

Hairline cracks

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Best route was laser drill small hole followed by short

PAMS pyro and then machine

Capsule after PAMS removal

Capsule after machining

Final Capsule after

release from mount

1 mm

1 mm

Laser hole

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First attempt to make the thick walled glass

capsules (>35 mm) resulted in shards and hemis

450ºC air pyro

Hemi post PAMS pyro

Nearly intact inner glass

capsule

Interface generated at Si-GDP

coating breakpoint

Interface (above) and intact inner

glass capsules (right) gave clues to

changes to be made for next

attempt

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1 mm

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No-breakpoint run went much better with mostly

intact capsules even after conversion to glass

~1mm x 60mm SiGDP capsule~700mm x 36mm glass capsule

Majority survived

PAMS pyro intact

Conversion in He/O2 (530ºC)

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Latest addition shows ranges of capsules made by the

Si-GDP process continues to grow

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= high probability of success

= made once

= success rateunknown

= actual batchsizes made

= most recentcapsule

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These examples demonstrate we are dedicated to

developing targets to meet the needs of the ICF community

1) Partially converted Glass Capsules doped with D

– Possibly of future interest but more development needed

2) Fully Deuterated Ge-GDP

– Successfully(?) made capsules >90% enrichment

(experiment in progress to confirm)

3) Glass capsule fill-tube assemblies

– CFTAs from Si-GDP glass solves issues associated with DT glass

4) Machined GDP/Si-GDP capsules for Shock-timing experiments

– Successful technique developed to provide high quality

mandrels

5) Thick-walled (>35mm) glass capsule for PSS experiments

– Mostly successful and extends the range of glass capsules

that can be made by the Si-GDP process