[PPT] - C. K. Li 25th Fusion Energy Conference St Petersburg, Russia 13 -18 PowerPoint Presentation

SLIDE 1

, ln ln

3He T E p D

i T k T k e k dx P d k dx d D i

B

                   

Classical diffusion Baro- diffusion Electro- diffusion Thermo- diffusion

𝛽 = 𝜍𝐸 𝜍𝑢𝑝𝑢 ~𝑔

𝐸

Rebound Shock:

𝛂𝑸 𝛂𝝔

iD

Gradients cause differential mass flux

i3He

vshock 𝛂𝑼

Mass flux

C. K. Li

25th Fusion Energy Conference St Petersburg, Russia 13 -18 Oct. 2014

SLIDE 2

► Ratios of T3Hed to D3Hep reaction yields, and DDp to DTn reaction yields quantitatively illustrate the fusion yield anomaly in directly driven, exploding–pusher ICF implosions. ► In contrast to the case of acceleration driven isothermal atmosphere during compression burn, shock driven ion diffusions cause specie separation at shock flash. ► Barodiffusion and electrodiffusion are likely the dominant effects. ► More detailed future work will focus on quantitative study

f each individual effect.

Measurements of 4 nuclear fusion products provide important information about the effects of ion diffusion

n the separation of fusion fuel species

Summary

This is an ongoing experiment project

SLIDE 3

R. Betti
D. Meyerhofer
J. Soures
P. Amendt
C. Bellei
D. Casey
S. Wilks

Collaborators

J. Frenje
M. Gatu Johnson
H. Rinderknecht
M. Rosenberg
F. Séguin
H. Sio
A. Zylstra
R. Petrasso

SLIDE 4

4

1. Lasers or x-rays irradiate and heat the outer surface of the capsule
4. Nuclear production

period (~100ps)

2. Ablation of the outer surface material accelerates the

inner part of the capsule inwards

3. As capsule compresses,

temperature and density increase

Ablation is used to generate the extreme pressures required to compress a capsule to ignition conditions

Neutron Alpha

DT gas DT gas DT ice

Ablator Hot-spot ignition requires a core temperature >10 keV and a fuel-areal density exceeding ~300 mg/cm2

SLIDE 5

5

𝜖𝜍 𝜖𝑢 + 𝛂 𝜍𝐰 = 0

𝜍

𝜖𝑤 𝜖𝑢 + 𝐰 ∙ 𝛂 v

v = 𝛂𝐊 × 𝐂 -𝛂𝑄 +

𝜍 𝑛F 𝑛 𝑜𝑓2 𝜖𝐊 𝜖𝑢 = E

E + v × 𝐂 -

1 𝑓𝑜 𝐊 × 𝐂 + 1 𝑓𝑜 𝛂𝑄𝑓 − 𝐊

𝜍 = 𝑜𝑗𝑛𝑗 + 𝑜𝑓𝑛𝑓 P = P𝑗 + Pe v =

1 𝜍 𝑜𝑗𝑛𝑗𝐰𝑗 + 𝑜𝑓𝑛𝑓𝐰𝑓

J J =𝑓𝑜 𝐰𝑗 − 𝐰𝑓

Single-fluid model Averaged quantities over all species

Mainline ICF simulations are made with average-ion hydrodynamic codes 𝜍 = 𝑜𝑗𝑛𝑗 + 𝑜𝑓𝑛𝑓 P = P𝑗 + Pe v =

1 𝜍 𝑜𝑗𝑛𝑗𝐰𝑗 + 𝑜𝑓𝑛𝑓𝐰𝑓

J J =𝑓𝑜 𝐰𝑗 − 𝐰𝑓 𝜍 = 𝑜𝑗𝑛𝑗 + 𝑜𝑓𝑛𝑓 P = P𝑗 + Pe v =

1 𝜍 𝑜𝑗𝑛𝑗𝐰𝑗 + 𝑜𝑓𝑛𝑓𝐰𝑓

J J =𝑓𝑜 𝐰𝑗 − 𝐰𝑓

SLIDE 6

Time Radius

Shock burn

Compression burn

Fuel-shell interface

500-800 ps

6

SLIDE 7

7

C. Bellei et al, Phys. Plasmas 20, 012701 (2013)

SLIDE 8

J R. Rygg et al., Phys. Plasmas (2008)

P. A. Amendt et al., Phys. Rev. Lett. 109 225001 (2010)

The effects of ion diffusion have been proposed to cause separation

f fuel species, leading to this

imbalance

The observed ICF fusion yield anomaly has been related to the imbalance of fuel species densities in the burn region

2 2

) 3 ( ~

D D n n

f f Y Y  

For the hydrodynamic equivalent mixtures, the scaled yields are

) 1 ( ) 3 ( ~

2 D D D p p

f f f Y Y   

SLIDE 9

Observation of self-generated radial electric fields in an imploded capsule has been made

0.8 ns 1.2 ns 1.4 ns 1.6 ns 1.9 ns 2.1ns

1015 1010 105

105
1010
1015

E (V/m)

Data Simulation t = 1.9 ns Pe ne Pe t = 0.8 ns Pe ne Pe

LILAC simulations by J. Delettrez

C. K. Li et al., PRL 100 225001 (2008)

SLIDE 10

Recent work by Amendt et al delineates the effects

f ion diffusion in plasmas of imploded capsule

             dx T d k T k eE k dx P d k P k D i

T B E p

ln ln ln

1 



Mass diffusivity flux

Classical diffusion Barotropic diffusion Electro diffusion Thermal diffusion

Classical diffusion coefficient k : Barodiffusion coefficient kp : Electrodiffusion coefficient kE : Thermaldiffusion coefficient kT :      

                      1 1

2 1 2 2 1 1

m m m Z m Z kE

          

 

   

       

  

1 / 1 1 / 1 1 1 1 / 1

2 1 2 1 2 1 2 1 2 2 1 1

                       m m Z m k Zm m m Z Z Z m m Z Z k k k k k

E p T

   

T T m m Z Z f T ZT T T Z m m k

e e e

/ , / , , , 1 1 1

2 1 2 1 2 2 1

  



                          

          

                      

2 2 1 1 1 1 2 2 1 1 1 2

1 1 1 1 1 1 1 m Z Z m Z Z m Z m Z Z Z k p      

P. A. Amendt et al., PRL. 109 225001 (2010)

PRL, accepted (2012)

SLIDE 11

11

Shock phase characterized by high temperature, moderate density, large λii, kinetic effects

from H. Robey

ρgas = 0.3 mg/cm3 Mshock ~ 10-50

1000 600 200 400 800 16 18 20 22 Time (ns)

Radius (µm) λii ~ 100 μm Mshock ~ 10-50 ρgas = 0.4 mg/cm3 OMEGA exploding pusher simulation Radius (µm)

D3He

SiO2[2.3μm]

λii ~ 100 μm

from A. Zylstra (HYADES)

NIF hot-spot ignition simulation

Rev 5 implosion

DT ice

CH [60μm]

DT vapor

SLIDE 12

12

Key measurements:

DD and D3He yields
Burn-averaged Ti
DD and D3He burn histories
DD and D3He burn profiles
Fuel ρR (ion density)
X-ray self-emission images (R)
Scattered light

Implosion Compact proton spectrometers

SLIDE 13

The first spectra of 4 nuclear reactions are simultaneously measured from a single capsule implosion that filled with DT3He gas

0.E+00 5.E+10

3 6 9 12 15 18 Energy (MeV) Yield / MeV

D-D p D-T alpha (X0.002) T-3He d (X50) D-3He p Shot 14972

15 atm DT3He 2.5 mm SiO2

SLIDE 14

The YT3HeD/YDHep and YDDn/YDT yield ratios are deviated from the predictions, qualitatively indicating the fuel stratification

0.01 0.02 0.03 5 10 15 20

T3HeD/D3Hep DDp/DT

SLIDE 15

D. T. Casey et al, Phys. Rev. Lett. 108, 075002 (2012).
1.E-17

1.E-03 2.E-03 3.E-03 4.E-03 5.E-03 6.E-03 5 10 15 YDDp/YDT Temperature [keV]

LILAC simulation

x10-3 5 4 3 1 YDD/YDT 2 6

data

0.E+00 2.E-03 4.E-03 6.E-03 8.E-03 5 10 15 YTT /YDT Temperature [keV]

Expected

x10-3

8 6 4 2 YTT /YDT

data LILAC simulation

While DD yields relative to the DT yield are lower than expected, TT reaction yields are higher than expected (assuming a constant density ratio ft /fd)

SLIDE 16

16

Hong Sio et al., to be submitted (2014)

SLIDE 17

17

Séguin et al., RSI (2004), PoP (2006)

Radius (µm) Radius (µm) DD-p or D3He-p image

3-MeV DD-p & 15-MeV D3He-p

Penumbra Tracks/cm2

Exploding pusher proton tracks / cm2 0E+0 1E+4 2E+4 3E+4 50 100 150

D3He DD

3x104 2x104 1x104

Reactions (µm-3)

2.3 mg/cm3 (Hydro-like) 0E+0 1E+4 2E+4 3E+4 50 100 150

D3He DD

3x104 2x104 1x104

Reactions (µm-3)

0.4 mg/cm3 (Kinetic-like)

Average Radial Burn Profiles

SLIDE 18

18

w/ Diffusion (Yieldx100) 100 Radius [mm] These results further demonstrate that ion diffusion is substantial in the long-λii implosio Simulations by P. Amendt, LLNL

Measured brightness profiles

D3He-p

Simulated brightness profiles

DD D3He Hydro

nly

0.E+00 1.E+06 2.E+06

50 100

Particles / μm2

Radius (µm)

Proton fluence [1/Area]

1x106 2x106

0.4 mg/cm3 (kinetic regime)

SLIDE 19

► Ratios of T3Hed to D3Hep reaction yields, and DDp to DTn reaction yields quantitatively illustrate the fusion yield anomaly in directly driven, exploding–pusher ICF implosions. ► In contrast to the case of acceleration driven isothermal atmosphere during compression burn, shock driven ion diffusions cause specie separation at shock flash. ► Barodiffusion and electrodiffusion are likely the dominant effects. ► More detailed future work will focus on quantitative study

f each individual effect.

Measurements of 4 nuclear fusion products provide important information about the effects of ion diffusion

n the separation of fusion fuel species

Summary