Studies of Vapour Shielding Physics in the OLMAT Facility. - - PowerPoint PPT Presentation

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Studies of Vapour Shielding Physics in the OLMAT Facility. - - PowerPoint PPT Presentation

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Studies of Vapour Shielding Physics in the OLMAT Facility. Applications to the LMD EuroFusion Project Francisco L Tabars Laboratorio Nacional de Fusion. Ciemat. Av Complutense 40 28040 Madrid. Spain OUTLOOK - Background. Motivation - The

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SLIDE 1

Francisco L Tabarés

Laboratorio Nacional de Fusion. Ciemat. Av Complutense 40 28040 Madrid. Spain

Studies of Vapour Shielding Physics in the OLMAT

  • Facility. Applications to the LMD EuroFusion Project
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SLIDE 2

OUTLOOK

  • TABARES. Vapour Shielding CRP. VIENNA 2019
  • Background. Motivation
  • The OLMAT Project
  • AM+LM Physics to address
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SLIDE 3

Power Load issues

  • TABARES. Vapour Shielding CRP. VIENNA 2019
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SLIDE 4

 No permanent damage (self healing)  Can be recirculated (power and T extraction)  Vapor shielding

Alternative: Liquid Metals in High Flux areas

  • TABARES. Vapour Shielding CRP.

VIENNA 2019

 Free flowing LM: continuous pumping out heat and particles But: MHD instabilities, magnetic viscosity  Splashing!  Grooved surfaces, slow motion: Uniformity, Wetting issues!

Proposed designs

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SLIDE 5

ITER design+Surface modification

  • TABARES. Vapour Shielding CRP. VIENNA 2019

Ts Ti Tc

d1 d2

q

CPS

Structure

Cooling

λ1 λ2 Ts (°)(Tw=150 ) 1% FLUX d1(mm) (CPS) d2(mm) (struc) P (MW/m2) Tin optim. 1277 1 3 28.75 Li optim. 480 (no redepos) 1 3 8.25

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SLIDE 6

Which LM?: Comparative analysis

  • TABARES. Vapour Shielding CRP. VIENNA 2019

Which LM maximizes conductive heat exhaust?

+

  • H retention
  • Material Compatibility
  • Cooling issues
  • Close Loop/refilling
  • Wetting
  • CPS design parameters
  • …..

Many answers already available from previous works Core plasma radiation/dilution water cooling? Maximum Liquid Li in vessel Need of impurity seeding? Stability of LiSn alloys…

Integration issues:

G max from code calculations:

+ sputtering

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SLIDE 7
  • TABARES. Vapour Shielding CRP. VIENNA 2019

1 1

4

1

5

1

6

1

7

1 1 1

4

1

5

L i ( 5 º C ) S n ( 8 º C )

Capillary Pressure Pa (full wetting)

p

  • r
  • u

s r a d i u s ( n m ) 1

  • 5

, 1 , 1 , 1 , 1 5 1 1 5 2 2 5 3 L i 2 m i c r

  • n

s L i 1 m i c r

  • n

s S n 2 m i c r

  • n

s S n 1 m i c r

  • n

s

thickness CPS (mm) refill time (s)

Standard CPS structure

Target Design with LM protection

Prefilled Modules, NSTX Holding Force+ refilling time

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SLIDE 8
  • TABARES. Vapour Shielding CRP. VIENNA 2019

The OLMAT Project Phase 1) NBI exposure of LM prototypes. Comparative studies (<200ms pulses, no ELMs) Phase 2) Addition of ELM-like loads (Laser pulses) Phase 3) Long NBI pulse ( up to 5 s)+ ELMs Phase 1)

  • LM ( Li, Sn , LiSn) and CPS structures tested

Project developed in three (overlapping) phases

Alternate use of TJ-II as a test bed and a magnetized fusion device for LM alternative target research

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SLIDE 9
  • TABARES. Vapour Shielding CRP. VIENNA 2019
  • RESOURCES. TJ-II

NBI-2 NBI-1

Heliac Stellarator 4 periods R=1.5 m <a>= 15-25 cm BT=1 T ECH : 2x300kW,53.2 GHz NBI:2x700 kW, >30 KeV Vol Plasma ~ 1m3 Low Z scenarios :

  • 2 Liq Lithium Limiters
  • First Wall Boronization
  • Vacuum Lithiation
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SLIDE 10
  • TABARES. Vapour Shielding CRP. VIENNA 2019

SPECIFIC FEATURES OF THE OLMAT PROJECT

  • Fully devoted to LM research
  • Large exposed area
  • DEMO relevant heat loads
  • Power Dep. profile adjustable
  • Long (150ms-few s)+short

(<1ms) pulses

  • High repetition loads

(1shot/2min+kHz ELM) (fatigue eff.)

  • Rotatable, refilled, heated +

cooled sample

OLMAT Features

Hot Plasma+ LM:

  • FTU: CLL, no NBI, narrow ports
  • ISTTOK: no NBI, small tokamak
  • COMPASS-U: Under design

EF Test Facilities:

  • GLADIS: No Li operation
  • JUDITH: e- beam. Raster.
  • PSI-2/ JULE: No Li operation
  • MAGNUM: Not fully devoted to LM
  • experiments. Small spot.

European Facilities

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SLIDE 11

NBI systems in TJ-II

  • TABARES. Vapour Shielding CRP. VIENNA 2019

 30 cm diameter duoPIGatron ion source. Beam spectrum: 55% E0, 25% E0/2 and 20% E0/3

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SLIDE 12
  • TABARES. Vapour Shielding CRP. VIENNA 2019
  • RESOURCES. NBI

Working gas Hydrogen Accel voltage 35 keV Accel current 60 A Decel voltage 1.5 keV Decel current 10 A Arc voltage 150 V Arc current 1200 A Pulse duration 150 ms Duty cycle ≤ 1 % Gas throughput 20-40Torr.l.s-1

NBI present Characteristics Possible operation w/o neutralizers: +35%

47,6oC 0,0oC

Figure 3: IR image of the Target Calorimeter after a NBI shot

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SLIDE 13

Power density achievable

  • TABARES. Vapour Shielding CRP. VIENNA 2019

Parametric Scans in I& V Ib at constant Vacc: Peaked Q profiles Vaccat constant Ib: From flat to peaked

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SLIDE 14

Final Design

  • TABARES. Vapour Shielding CRP. VIENNA 2019
  • Devoted exposure chamber
  • Sample preparation pre-chamber
  • Linear manipulator w long drive

heating and rotation

  • Sample holder: 250 mm diam.

Laser NBI

Pulsed Laser : Fiber type 0.5 GW/m2

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SLIDE 15

Chamber design

  • TABARES. Vapour Shielding CRP. VIENNA 2019

DIAGNOSTICS

  • OES: Stark broadening, Impurity,

line ratio (He beam), etc…

  • Langmuir probes
  • TCs
  • Calorimetry
  • IR camera
  • Pyrometers
  • Laser detachment?
  • LIBS? (NdYag Laser available)
  • VUV spectroscopy
  • Bolometry
  • SXR
  • ….
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SLIDE 16
  • TABARES. Vapour Shielding CRP. VIENNA 2019

Performance of Liquid Metal-based targets during slow transients up to Power Fluxes of 20 MWm-2. LMs: Li, Sn and LiSn. Comparative study Impact of the CPS design on its ability to withstand high power fluxes. Combined effect of ELMs and high, steady, power fluxes on the LM target. In situ determination of the surface refilling time for each CPS structure (KHz laser) Effect of H content on theses parameters at levels below the sat. solubility limit. Stability of LiSn alloys in the presence of strong redeposition. Redeposition efficiency of ejected material.* Radiation of the local plasma at high concentrations of LM constituents.*  AM Physics of vapor shielding phenomena * Extrapolation to divertor plasmas through modeling

Expected deliverables :

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SLIDE 17

EXAMPLES

  • It has been proposed that PvapLM~Pplasma leads to T clamping (vapour

shielding)

  • In DEMO Pplasma:10-100Pa
  • For Li: 612-722 ºC, For Sn: 1000-1250 ºC
  • PnT in OLMAT up to 45 Pa: Different possible combinations of Flux+

Energy/ptcl. Different plasma parameters. Address vapour shielding physics

  • TABARES. Vapour Shielding CRP. VIENNA 2019
  • Vapour shielding/ T clamping
  • Redeposition

In linear Plasma devices: Gas Gas redep 1-2 cm In OLMAT >15cm plasma Plate analysis Plasma parameters

DEMO

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SLIDE 18
  • TABARES. Vapour Shielding CRP. VIENNA 2019

Complex interplay of solid and AM +Plasma Physics Not fully understood!!

AM+LM Physics to address

+ He, H+, Li2,..

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SLIDE 19
  • TABARES. Vapour Shielding CRP.

VIENNA 2019

VS Models

Three models analysed by Skovordin et al. (PoP 2016)

  • 1) Reduction of power by “optical depth” of VS Plasma
  • 2) Prad ~N of ptcls in VS Plasma
  • 3) Size of Vapour cloud matters

Emax abs not a validation parameters for the model. Look for total evaporated flux.  PISCES B: Light impurities (Be) penetrate the plasma and induce cooling. Not for W, Mo MK-200

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SLIDE 20

T-10: >10MW/m2 Magnum PSI: 7-8 MW/m2

Morgan, Rindt..

Vapour Shielding in Li

  • TABARES. Vapour Shielding CRP.

VIENNA 2019

FTU: 5-14 MW/m2

GLi :100x (600-900ºC) Why Tw higher in Divertor-like plasma?  Prad by Li ions?  P plasma?  Plasma species (H vs He)  Mag Field effects?  Etc..

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CR Model Li. Fixed tau

  • TABARES. Vapour Shielding CRP. VIENNA 2019

Only e- collisions included!

Goldston 2016

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SLIDE 22

CR non coronal eq.

  • TABARES. Vapour Shielding CRP. VIENNA 2019

Lazarev EPS 99

Te vapour plasma??

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SLIDE 23

Sensitivity to Atomic Radiation models

  • TABARES. Vapour Shielding CRP. VIENNA 2019

1: 10-8 2: 10-9 3: 10-10

Erad/ptcl (W) Differences on the required evaporation rate, not in the achievable power screening

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SLIDE 24
  • TABARES. Vapour Shielding CRP.

VIENNA 2019

Specific items for Li surfaces.

1) Sputtering 2) SEE 3) H- reflection 1) Alkali surfaces: 2/3 of sputter as ions

J.P. Allain, PhD Thesis

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SLIDE 25
  • TABARES. Vapour Shielding CRP.

VIENNA 2019

2) SEE: Enhanced SEE observed in Li exposed to He, Ar and HGD plasmas Also seen in LiSn and in H plasmas Effect of surface oxidation?

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SLIDE 26
  • TABARES. Vapour Shielding CRP.

VIENNA 2019

3) Reflection of negative ions

Isotope effect

D+

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SLIDE 27

Heavy particle processes

  • TABARES. Vapour Shielding CRP. VIENNA 2019

Interaction of H with Li vapour. H+Li  Li++H+ e-  Li++H- H++Li  Li++H  Li++H++e- H+Li+  H++Li (Li++e-) H-+Li+ H+ Li H (H+) +Li2

(+) prods

Strong isotopic effect

Atomic data for fusion. Volume 1: Collisions of H, H2, He and Li atoms and ions with atoms and molecules. Barnett, Clarence F.et al.July 1990 Bibcode: 1990STIN...9113238B Li++H(D,T)

LF Errea et al, Physical Review A, 2008 - APS

+ excitation/de-excitation processes BUT: Sn AM database: ???

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SLIDE 28

SnI at 380 nm

  • TABARES. Vapour Shielding CRP. VIENNA 2019

Vasallo et al. 2017 From LIBS experiments

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Rational for VS experiments

  • Calorimetry: net heat to the target
  • Power screened/ evaporation rate at the measured Tw

W/prtcle+ plasma parameters CR Model!!

  • Check for consistency: redeposition
  • Add AM processes
  • Recheck Design direct proof test.
  • Change LM, power, etc…
  • What the accumulated errors would be?
  • TABARES. Vapour Shielding CRP. VIENNA 2019
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SLIDE 30

Rational for VS experiments

  • TABARES. Vapour Shielding CRP. VIENNA 2019
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SLIDE 31
  • TABARES. Vapour Shielding CRP. VIENNA 2019

Ts Ti Tc

d1 d2

q

CPS

Structure

Cooling

λ1 λ2

Power Exhaust Issues

Ts (°(Tw=150 ) 1% FLUX d1(mm) (CPS) d2(mm) (struc) P (MW/m2) Tin optim. 1277 1 3 28.75 Li optim. 480 1 3 8.25

But: Thermal conductivity CPS+Li?: optimize structure

Maximum T Li?: Redeposition efficiency + T retention Coenen et al Phys. Scripta 2014

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SLIDE 32

LLL in TJ-II

  • TABARES. Vapour Shielding CRP. VIENNA 2019
  • Two LLL installed in TJ-II ( heated, movable, diagnosed)
  • Spare manipulator system,1 m drive, motorized
  • To be recycled (adapted) for OLMAT LM target positioning
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SLIDE 33
  • TABARES. Vapour Shielding CRP. VIENNA 2019

Resources not available

Laser System: ELM simulation+ CW heating if required

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SLIDE 34
  • TABARES. Vapour Shielding CRP. VIENNA 2019

For Li add:

  • Anomalous enhanced SEE
  • Reflection of neg. ions, H-
  • Sputtering as Li+

Complex AM & Plasma Physics!!

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SLIDE 35

Evolution of Fusion Devices

  • TABARES. Vapour Shielding CRP. VIENNA 2019

Power density to the target continuously increasing!!

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SLIDE 36

Material Challenge

  • TABARES. Vapour Shielding CRP. VIENNA 2019

Several activities oriented to make W (composites) DEMO compatible… (see i.e., G. Dinescu…)

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SLIDE 37

Limitations (some)

 Lack of actual Divertor plasma scenarios. Need of modelling. Restricted to comparative studies of LM, CPS, closed loop… in some instances.  Limited pulse duration (time for SS Temp 2-5s)  Disruption power loads achievable only in a small area  REAL DIVERTOR PLASMA EXPOSURE STILL MANDATORY

  • TABARES. Vapour Shielding CRP. VIENNA 2019

Raclette modeling