Status of HAPL Tasks 1 & 3 for University of Wisconsin

Gregory Moses

Milad FatenejadFusion Technology Institute

High Average Power Laser Meeting

September 24-25, 2003

Madison, WI

Numbers

010010101101011100010101010101010100101011010010110001010100101001010101010101010010100100000100101100110001001001000001111101000100100101010010101010001001010101010001000010111010100101001000101111011001010001010101001010001010100100111010010101100100101001000101010010101110100100101010010101100101010101010001010101011010100101010101001010011001001010101010101010110010100101001011100101000001100110011010101100110010101010101010100101010100100100101010110100010100111101010101001010010100010010101101011011001010010100101010101010010101001000010001010101010001010111101010101010010101

Outline

• BUCKY-ANSYS coupling (Task 3)– Task 3—couple BUCKY output to ANSYS input so

that a large number of cases can be examined in a short time using CONDOR

• Modeling target ion threat spectrum for chamber response studies (Task 1)– Task 1—simulate target output spectra with BUCKY

and improve underlying models to more reliably compute threat spectra

• Energy spectrum• Time of arrival

Task 3 -- Stress Analysis

BUCKY target

simulation- implosion,

burn, explosion

BUCKYchamber simulationincluding

wall response

BUCKYchamber simulation

withoutwall response

Vaporization, wall temperature history

Heating rate density q(r,t)

ANSYS thermalstress simulation

Stress/fatigue design criteria

New capability

Old capability

Stress analysis

RRP

Task 1 -- Modeling target ion threat spectrum

• Historical reminder of Carbon wall analysis– HAPL Meeting December 2002– HAPL Meeting April 2003

BUCKY simulations of chamber response allow the prediction of first wall surface temperature evolution.

• Roughly speaking, there are three peaks in the first wall temperature:

1) A response to the prompt, unattenuated x-rays hitting the wall (heating it practically volumetrically, in the case of a graphite first wall).

2) Response to soft xrays re-radiated after the Xe slows and captures the least penetrating ions.

3) Bursts of temperature rise as the unstopped ions strike the wall. This effect is somewhat exaggerated in these simulations due to the coarse binning of the ion spectum.

Surface Temperature Evolution, 80mTorr Xe,

650cm radius graphite wall, PD_EOSOPA target

1000

1500

2000

2500

3000

3500

1.E-08 1.E-07 1.E-06 1.E-05

Time (s)

Su

rfac

e T

em

pe

ratu

re (

C)

1

2

3

D. Haynes, HAPL Dec 2002

Ion binning: For compatibility with earlier studies, ion spectra were divided into 15 energy bins. This led to an overestimatein the temperature rise due to ions.

•Increasing the detail in the reproduction until the wall response converges indicates that this led to an conservative definition of the operating window.

Deuterium ion binning effect on simulated wall response

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

0.26

1.E-07 2.E-06 4.E-06 6.E-06 8.E-06

Time (s)

Tem

pera

ture

(eV

)

Coarse binning

Resolvedbinning

Though brief, the spurious temperature excursions can lead to

unphysical mass loss or melting.

However:

500C

D. Haynes, HAPL Apr 2003

Conclusions

•Two approximations in previously reported BUCKY/CONDOR studies were examined:

•Looking only at shot 1 underestimated the starting temperature of the armor surface; and,

•Coarse binning of ion spectrum overestimated mass loss.

•These two approximations compensated for each other, at least for the carbon wall case considered.

•Thus, operating windows previously reported for C walls are still in force through serendipity.

•Yield was added as a dimension in the space of chamber design parameters.

•A single figure of merit for ion deposition effects needs to be carefully applied, as differences in spectrum change temperatures and gradients within the wall.

•Two approximations in previously reported BUCKY/CONDOR studies were examined:

•Looking only at shot 1 underestimated the starting temperature of the armor surface; and,

•Coarse binning of ion spectrum overestimated mass loss.

•These two approximations compensated for each other, at least for the carbon wall case considered.

•Thus, operating windows previously reported for C walls are still in force through serendipity.

•Yield was added as a dimension in the space of chamber design parameters.

•A single figure of merit for ion deposition effects needs to be carefully applied, as differences in spectrum change temperatures and gradients within the wall.

D. Haynes, HAPL Apr 2003

Ion Debris Spectra

Ion Energy (eV)

#o

fIo

ns

103 104 105 106 107

1016

1017

1018

1019 DTHCPdHeHe - burn

Pd Layered TargetEOSOPA

Each ion spectrum approximated by 15“representative” energies

Ion heating source is not temporally resolved

Volumetric Heating Rate vs Cycle (zone 2)

1.00E+10

1.00E+11

1.00E+12

1.00E+13

1.00E+14

1.00E+15

1

2040

4079

6118

8157

1019

6

1223

5

1427

4

1631

3

1835

2

2039

1

2243

0

2446

9

2650

8

2854

7

3058

6

Cycle

Vo

lum

etri

c H

eati

ng

Rat

e (W

/cc)

~1-10 sTime of flightto first wall

Increase “resolution” of spectrum

Volumetric Heating Rate vs Cycle (Zone 1 - n energies)

1.00E+03

1.00E+05

1.00E+07

1.00E+09

1.00E+11

1.00E+13

1.00E+15

1

1494

2987

4480

5973

7466

8959

1045

2

1194

5

1343

8

1493

1

1642

4

1791

7

1941

0

2090

3

2239

6

2388

9

2538

2

2687

5

2836

8

2986

1

Cycle

Vo

lum

etri

c H

eati

ng

Rat

e (W

/cc)

Volumetric Heating Rate vs Cycle (Zone 1 - 2*n energies)

1.00E+03

1.00E+04

1.00E+05

1.00E+06

1.00E+07

1.00E+08

1.00E+09

1.00E+10

1.00E+11

1.00E+12

1.00E+13

1.00E+14

1

1381

2761

4141

5521

6901

8281

9661

1104

1

1242

1

1380

1

1518

1

1656

1

1794

1

1932

1

2070

1

2208

1

2346

1

2484

1

2622

1

2760

1

2898

1

Cycle

Vo

lum

etri

c H

eati

ng

Rat

e (W

/cc)

15 representative ions 30 representative ions

Future plans

• We are now capable of doing large parameter sweeps involving complex lengthy calculations. Hands-off analysis.

• We must focus on correctly doing the right calculations.

• Need better characterization of x-ray and ion spectra for all ions and relevant target designs. (Target threat group?).