Plasma Facing Components (PFCs)€¦ · ASIPP Plasma Facing Components (PFCs) for Magnetic Confined Fusion Devices G. -N. Luo Division of Fusion Reactor Materials Science & Technology

ASIPP

Plasma Facing Components (PFCs) for Magnetic Confined Fusion Devices

G. -N. Luo

Division of Fusion Reactor Materials Science & Technology

Institute of Plasma Physics, CAS, Hefei, Anhui, 230031 China

Joint ICTP/CAS/IAEA School & Workshop on PMI

in Fusion Devices, July 18-22, 2016, Hefei, China

ASIPP

Outline

Fusion reactor

What are PFCs

PFCs for EAST

PFCs for ITER

PFCs for DEMO

2016/7/18 Plasma Facing Components 2

ASIPP

Outline

Fusion reactor


ASIPP

Roadmap for Magnetic Fusion

Non-nuclear

facilities for

engineering

design/test

20??

CFETR/DEMO

Current devices

Fusion Power Plant

EAST HL-2M 2025

2030’sITER

Nuclear facilities,

CMIF/IFMIF, etc. for

materials & tritium

China


ASIPP

China Fusion Engineering Testing Reactor (CFETR)


Blanket

Divertor

Cryostat

Port plug

CD & H

SC Magnets

CASKVacuum vessel

Diagnostics

And tritium plant, power supplies, vacuum, cooling, cryogenics,

remote handling, hot lab for maintenance, etc., subsystems!

ASIPP

Outline

What are PFCs?


ASIPP

What are PFCs?


• PFCs are components facing directly the high T plasmas,protecting vacuum chamber and other in-vessel components

• PFCs comprise large-area first wall and divertor surfaces, as wellas smaller but vital systems (startup limiter, antennas)

• PFCs must withstand intense plasma heat & particle fluxes, andfunction with high n wall loading & bulk nuclear heating

Key requirements

• Low surface erosion from sputtering and plasma transients

• Low plasma contamination & Long surface/structural lifetimes

• Minimum tritium retention or permeation & nuclear activation

• Strong enough resistance to electromagnetically induced loads

ASIPP

Major PFCs – FW & divertor

Blanket system

Particle flux ~1020/m2s

Heat flux 0.5~2MW/m2

Neutron wall loading 0.5~1.5MW/m2

Area 800-1000m2

Particle flux 1022-1024/m2s

Heat flux 10~20MW/m2 (SSO)

Area Whole: ~100m2, Strike point: ~0.1-1m2


First wall

Divertor system

ASIPP

Harsh environments

Extreme T

& gradientsSC CoilsFW/DivEdge PlasmaCore Plasma

～108 K ～105 K ～103 K ～3 K

5.7m


ASIPP

Harsh environments

Magnetic field

High field side : 10-18T

Core space: 6-10T

Low field side : 4-6T

Variation with space : several T/m

Variation with time : several T/s +


ASIPP

Key issues of PFCs

• Choice of materials and coolants

• Joining of PFM and heat sink material

• Capability of power handling (HHF testing)

• Reliability and integrity of PFCs in operation

• Effect of neutron irradiation on the joints

• Quality control of mass production

• …………


The PFCs will be crucial both for achievable plasma performance & machine availability!

ASIPP

Materials for PFCs

PFM – carbon based (C & CFC), beryllium, refractory (W & Mo)


C/CFC Be W (Mo)

Advantage

1. Low Z material2. Compatible with

plasma3. No melting

1. Low Z material2. Medium retention3. Oxygen uptaker

1. Lowest sputtering2. Highest melting point3. High thermal conductivity4. Low retention

Disadvantage

1. High sputtering 2. Chemical erosion3. High codeposition4. High retention

1. Low melting point2. High sputtering3. Toxicity

1. High Z material2. Brittle material3. H/He effects

Heat sink – CuCrZr alloy and RAFM steels (possible ODS-strengthened)

CuCrZr RAFM

Advantage1. High thermal conductivity2. Good mechanical properties

1. Low neutron activation2. Good mechanical properties

Disadvantage

1. Degradation of mechanical properties after annealing

2. Radiation hardening3. Neutron activation

1. Low thermal conductivity2. Difficult in joining (especially for

the ODS ones)

ASIPP

Cooling for PFCs


Coolant Inertial Water Helium

Advantage

1. Easy to

manufacture,

inspect and

install

2. No leakage risk

1. High capability of

power handing

(20MW/m2)

2. Good performance

of steady state

heat flux

1. Medium capability

of power handing

(10MW/m2)

2. Feasibility of high

temperature wall

operation

Disadvantage

1. Low capability

of power

handling

1. Difficult to join

PFM and heat sink

2. High temperature

gradient of PFCs

1. Very difficult to

manufacture and

inspect

2. Low reliability

• Inertial cooling – power removal via heat capacity & radiation• Active cooling – heat removal by pressurized water or helium

ASIPP

Water cooled PFCs – flat plate

• Advantage:

– High heat transfer capability

– Easy to manufacture and inspect

– Withstand heat loads of ~5MW/m2

• Disadvantage:

– Singularity of thermal stress

– Peeling-off in case of interface failure


Flat plate PFC w/ hypervapotroncooling structure

Flat plate PFC w/ round cooling tube

HIP / VHPVPS/CVD/PVD

VHP/

Brazing

or pure Ti or filler interlayer

or Be or C

ASIPP

Water cooled PFCs – monoblock


• Advantage:– Lower thermal stress than flat plate

– Intrinsic safety in case of failure (no peeling)

– Withstand heat loads of 10-20MW/m2

• Disadvantage:– Difficult to manufacture and inspect

– Very expensive

BrazingHIP & HRP (diffusion bonding)

AMC (CFC)Brazing (CFC)Direct Cu casting

CFC or W

CuCrZr tube

Cu interlayer

ASIPP

Helium cooled PFCs – design

• High wall temperature to reduce hydrogen retention and recycling

• Pressurized helium jetting flow to reinforce heat transfer capability

• Difficult to manufacture and inspect


M.S. Tillack, et al, FED 86 (2011) 71-98

P. Norajitra, et al, JNM 386-388(2009)813-816

ASIPP

Thermal stress – analyses

• Large difference of thermal expansion btw PFM and heat sink (HS)

• Debonding of PFM/HS joints• Leaking of HS and other joints


0

2

4

6

8

10

12

14

16

18

Be CFC W

1E

-6 m

/m

Cu alloy

Thermal expansion coeff. at 3000C Thermal stress distri. at 20MW/m2

F. Crescenzi, et al, FED 89 (2014) 985-990

ASIPP

Electromagnetic (EM) loads

• Plasma instabilities such as disruptions and vertical displacement events (VDEs), give rise to severe EM transients, and thus strong forces on PFCs and other in-vessel components.


• These can be calculated via combining the plasma simulation code like DINA for time variation of plasma and halo currents, with the finite element code like ANSYS-EM. Sunil Pak, et al, FED 88 (2013) 3224-3237

ASIPP

PFCs for EAST


ASIPP

PFMC evolution in EAST


W

Mo

C

Mo

Mo

Full C PFC Mo-FW + C-Div

2008 2012

1st plasma

2014

W&C-Div+Mo-FWFull SS PFC

2006

C

2018~2019 / Full W PFC

WW

C C

ASIPP

Design of W/Cu divertor


EAST goal: long-pulse high performance plasma operation

Conceptual design Engineering design

ASIPP

Design of W/Cu PFCs

• 15000 Monoblocks

• 720 Monoblock PFUs

• 240 Flat type PFUs


Dual chamfering for EAST

80 Cassette Bodies

ASIPP

Flowchart of manufacturing


W powder

W compact

sintering

rolling

W plate

Cu,Cr&Zr

Ingot

melting

CuCrZr platerolling

Cu,Cr&Zr

Ingot

melting

CuCrZr tubesdrawing

W block W bar

Pure CuHIP HIP

W/Cu monoblock

NDT NDT

NDT

W/Cu slice

HIP Machining

W/Cu mono-block PFUs Baffle Dome upper Dome lowerpanel

EBW of two halves+legs+in/outlets

DOME

EBW of endcup+PFUs+trans-plate+baffle+legs+in/outlets

Target

Assembly to CB and in-vessel installation

He leak check at 1.5MPa/180℃

HIP

NDT+leak check

NDTNDT

NDT

Raw mater.

PFU manuf.

Assembly

ASIPP

ITER-like monoblock W/Cu PFC


• W/Cu monoblocks prepared employing Hot Isostatic Pressing (HIP) technology (9000C, 100MPa)

• W/Cu PFUs manufactured successfully by HIP technology (6000C, 100MPa), properties of CuCrZr after HIP satisfy the requirement

• US-NDT results: Bondings between monoblocks/OFC/CuCrZr excellent

Annealing behavior of CuCrZr tube

ASIPP

Flat-plate W/Cu PFCs

• Casting + HIP: The interface of W/Cu were joined by casting (1200⁰C), and then the interface of Cu/CuCrZr was bonded by HIP at lower temperature of 500~600⁰C.

• NDT results: bondings between W tiles/OFC/CuCrZr plate excellent

252016/7/18 Plasma Facing Components

BAFFLE

Plate

ASIPP

Parts joining: E-beam welding

2016/7/18 26

• Joining between monoblockunits with endbox/manifold and flat baffle

• Joining of two-half parts for dome structural design

• Supporting legs and inlet/outlet cooling tubes joined to CuCrZrheat sink

• EB: 60kV, max 100mA; Seam: > 3mm deep, ~1mm wide at surface

1.2 mm

3.1 mm

CuCrZr

Plasma Facing Components

ASIPP

E-beam HHF testing

W/Cu monoblock PFU: survived 1000 cycles of heat load of 10MW/m2, cooling water of 4m/s, 20⁰C, 15s/15s on/off cycles

W/Cu flat type mock-up: 1000 cycles, 5MW/m2, 4m/s, 20⁰C


ASIPP


US-NDT for W/Cu PFCs

US-NDT for

monoblock PFU

NDT for flat

type PFU

• Single probe: scanning the inner surface

• The defects of Φ1mm in the interface of W/Cu and Cu/CuCuZr was detected clearly using this set-up

• 15000 W/Cu mono-blocks and 720 PFUs tested

• More than 30000 W/Cu slices and 240 flat PFUs have been tested by this set-up with detection limit of Φ1mm

ASIPP

Helium leak detection for PFCs


• Evaluation of welding quality and reliability for EAST OVT, IVT and DOMEcomponents

• During baking: @ 180⁰C for 20 min under 1.5 MPa (He inside)

• Background vacuum: < 5.4x10-3Pa; leak level: 2x10-11 Pa.m3.s-1

• Acceptance criteria: 1x10-10 Pa.m3.s-1

• 240 components (80 OVT, 80 IVT, 80 DOME) were tested

ASIPP

W(upper) + C (lower) divertors + Mo-FW


W

C

Mo

ASIPP

H port dedicated to PWI research on EAST

- Maximum sample weight: 25kg

- Sample holder moving velocity:

1- 15mm/s

- Maximum sample diam.: 500mm

- Can insert into LCFS

- Sample water-cooling & heating

- Gas puffing system

- Diagnostics: Langmuir probes,

thermocouples, spectroscopy, …

Material and Plasma Evaluation System

(MAPES)


ASIPP

Multiple diagnostics for PWI research on EAST

attached detached

Divertor detachment

Multichannel optical system

Divertor gas

puff system

Edge Langmuir probes

Laser Induced

Breakdown

/Ablation

Spectroscopy

(LIBS/LIAS)International collaboration

High resolution

spectrometer

Post-

mortem

analysis


ASIPP

W monoblock shaping


# 52102

Outer divertor

Tolerance of W PFC surface- Toroidal: 2 mm- Neighbor: 0.5 mm Monoblock shaping

- dual 1mm×1mm chamfering

W monoblockgeometry optimization for steady condition

X.H. Chen et al, FED 2016

Bt

ASIPP

Effective W Sputtering Yields in EAST


W erosion yield governed by C ion bombardment

Better W erosion yield suppression by Li coating

compared to Si one, lower than those in ASDEX

Upgrade, but still higher than that in JET

ASIPP

ELM Dominated W Erosion in H Mode Discharge


-10 -5 0 5 10 15

0

2

4

6

0

2

4

6

8

10

12

14

R-Rosp

(cm)

W atom (intra-ELM)

W atom (inter-ELM)

Js (intra-ELM)

Js (inter-ELM)

EAST #: 59950 DN / 2.3T

W a

tom

flu

x 1

01

9 /

(m

2 s

)

Js (

A /

cm

2)

W erosion during ELM accounts for about 70%

of total W erosion amounts in an ELM cycle on

average.

Intra-ELM W influx arises from proximity of

outer strike point and Inter-ELM W flux peaks

slightly away from outer strike point.

0

0.5

WI 400.9nm

2016 EAST Shot: 59950

0

2

CII 426.7nm

10

13 p

ho

to

ns

/(s

cm

2 s

r)

0

1

2Si II 413.1nm

0

10Js

A c

m-2

4.4 4.45 4.5 4.55 4.6 4.65 4.7 4.75 4.8 4.85 4.90

0.5

1

Time ( s )

MW

m-2

Peak q

ASIPP


PFCs for ITER

ASIPP

ITER PFCs

• PFCs in ITER are mainly divided into two regions based on their different functions:

– Shielding Blanket (First Wall)

– Divertor

• All of PFCs are designed as multi-modules, which can be installed and uninstalled by remote handing, considering future radioactive case.

• ITER is a Nuclear Facility INB-174 (in France).

(First Wall)

2016/7/18 37Plasma Facing Components

ASIPP

FW(Blanket)

• Major functions:– Absorbing radiation and particle heat

fluxes from the plasma– Contribute to shielding to reduce heat and

neutron loads in the vacuum vessel and ex-vessel components

– Provide limiting surfaces that define the plasma boundary during start-up and shutdown

– Provide passage for the plasma diagnostics• Procurement:

– First wall (NHF) – EUDA ~50%– First wall (EHF) – RFDA ~40%, CNDA ~10%– Shield block – CNDA ~50%, KODA ~50%– Blanket modules – RFDA ~40%

• Materials – FW: flat Be/Cu/SS; Shield block: SS


FW

Block

Block

FW

ASIPP

FW/Blanket


B. Bigot, Progress towards fusion at ITER, ICFRM-17, Aachen, Germany, 11-16 Oct. 2015

ASIPP

Divertor

• Major functions:

– To minimize the impurity content of the plasma

– To absorb radiation and particle heat fluxes from the plasma while allowing neutral particles to be exhausted to the vacuum system

– Provide passage for the plasma diagnostics

– Provide shielding to VV and external components

• Procurement:

– Outer Vertical Target – JADA

– Inner Vertical Target – EUDA

– Dome –RFDA

– Cassette and Integration – EUDA


B. Bigot, Progress towards fusion at ITER, ICFRM-17, Aachen, Germany, 11-16 Oct. 2015

ASIPP

Divertor

• Vertical Target Plasma-Facing Unit

– Monoblock with swirl tape at high heat flux handing area

– W armour/OFCu/CuCrZr-IG

– Tube to tube joint CuCrZr-IG/ Alloy625/ 316L pipe

• Dome Plasma-Facing Unit

– W/Cu flat tile with CuCrZr/316L(N)-IG hypervapotron coolant channel


ASIPP

Divertor


ASIPP

Divertor


ASIPP

Divertor


ASIPP

High Heat Flux Testing

Location: Efremov Institute, St-

Petersburg, Russia

Purpose: Performance and series tests

of Divertor PFCs

Operating principle: HHFT of

component’s surface by e-beam

Maximum beam power: 800 kW

Maximum accelerating voltage: 60kV

Vacuum level: 10-5 mbar

Advanced system of diagnostics


ITER Divertor Test Facility (IDTF)

R.A. Pitts, et al., 18th ITPA DivSOL Topical Meeting, Hefei, China, 19-22 March 2013

ASIPP

HHFT on OVT PFUs

• Heat loads: 10s on and 10s off

• Target of Thermal hydraulic parameters:

Inlet: 3.9 MPa; 11 m/s; 70 ⁰C to be used in ITER


5 x 4 monoblocks

Window type mask

• Straight W part of PFUs subjected to the tests:

20 monoblocks of 12mm (axial) x 28mm(poloidal) x 8 mm (thickness at the top of the tube)

ASIPP

HHF test results

• No significant increase of Tsurf

observed for 5000 cycles testing at 10MW/m2

• No sudden crack openings at the W/OFC-OFC/Cu joints during whole testing


300 400 500 600 700 800 900 1000

1900

1950

2000

2050

2100

2150

Te

mp

era

ture

, [0

C]

Number of cycle

Normal (IR) (13 tile) Hottest (IR) (15 tile) Pyrometer (13 tile)

Average surface temperature

Successfully withstand 5000 cycles at10MW/m2 + 1000 cycles at 20MW/m2

20MW/m2

ASIPP


PFCs for DEMO

ASIPP

DEMO PFCs

• Higher heat flux, longer pulses, higher duty factor

‒ 4x ITER’s heat flux

‒ 5000x longer pulses

‒ 5x higher even short-term average duty factor

• Erosion, dust production, tritium retention and component lifetime issues are

much more challenging due to DEMO’s mission

‒ DEMO must show practical solutions that allow for continuous operation for

at least 2 full-power years between PFC change outs

‒ ITER plans to change out divertors after ~ 0.08 full-power years – at much

lower power

• Many solutions used on ITER are not Demo-relevant

‒ Moderate fraction of radiated power

‒ Intermittent dust collection and tritium clean-up


DEMO presents a much larger PMI challenge than ITER!

ASIPP

Helium cooled finger concept


10 MW/m2

P. Norajitra, IHHFC,San Diego, CA, USA,Dec 10-12, 2008

ASIPP

Jet Impingement


Heat transfer coefficient

(Low Re Number)

0

10000

20000

30000

40000

50000

60000

70000

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

R, mm

HtC

, W

/Km

2

k-e Suga's cubic

k-w

v' Spalart-Allmaras

Distance from Jet Center [mm]

htc

[W

/m²K

]

Multi-jet

Single-jet

ASIPP

Helium cooled T-tube concept

• Heat flux ~10MW/m2

• The max helium jet velocity ~230m/s

• Maximum heat transfer coefficient ~ 4.19×104W/m2K

• The maximum temperature of the W armor~1782⁰C


M.S. Tillack, et al, FED 86 (2011) 71-98

ASIPP

Water cooled monoblock concept

• W is considered as the armour material with T operating window 500-1300⁰C

• Eurofer as heat sink material (325-550⁰C)

• Cooling water: 325⁰C, 20m/s, 15.5MPa


Marianne Richou, et al., FED 89 (2011) 975-980

ASIPP

Summary

• PFCs are crucial both for achievable plasma performance & machine availability!

• EAST has achieved a full tungsten upper divertor, maybe full W-PFC in 2-3 years.

• ITER is finalizing its W-divertor design, and also validating the PFCs’ prototype technologies.

• Fusion society has started conceptual activities for DEMO PFCs, still long long way to go!


ASIPP

Thanks!


Documents

Plasma Facing Components (PFCs)€¦ · ASIPP Plasma Facing Components (PFCs) for Magnetic Confined Fusion Devices G. -N. Luo Division of Fusion Reactor Materials Science & Technology