Diagnostics R&D for DEMO Taking into account results from Varenna Workshop

Francesco Paolo Orsitto ENEA Fusion Technical Unit , CR Frascati (Italy)

2nd IAEA DEMO Programme Workshop IAEA Vienna 17-20 dec 2013 Contributors : P Thomas, W Biel, T Donne, A Costley, W Morris, TN Todd,R Imazawa, K Itami, R Felton, V Kiptily, A Murari, G Vayakis, C Vukolov, I Duran, S Lilley, D Pacella, R Villari, F Moro, C Sozzi, M Pillon, D Milocco,M de Baar, F Felici, R Wenninger, A Silva, M Tardocchi, G Gorini, M P Petrov, A Krasilnikov.

Motivations

Initiatives for DEMO Diagnostics ideally linked 1.EFDA PPP&T WP13-DAS04 DEMO diagnostics and Instrumentations project : EU WG to define an R&D programme and feasibility of specific systems ( magnetics, polarimetry, neutronics, ECE and reflectometry). 2.Varenna Workshop Fusion Reactor Diagnostics (9-12 september 2013). The Traditional Varenna appointment of the worldwide diagnostics community The sessions building blocks of Varenna Workshop were : •programme of development of Diagnostics for DEMO Device CONTROL ( machine protection and Basic scenario control) • including subsystems like blanket and Heatings • considering an accompanying programme on JET/ ITER and other devices in operation

Outline

1. DEMO mission and Strategy / Main MESSAGES

2. Engineering and technical Constraints

3. Machine protection and basic control/Minimum DIA set vs Physics based control concepts

4. MHD , Burn and Divertor Diagnostics and control analysis

5. Readiness level and R&D needed

6. Planning of DEMO relevant development on devices and facilities

7. conclusions

MAIN MESSAGES •DEMO diagnostics should focus on high priority parameters: diagnostics for machine protection and basic control to be useful for BURN control in long pulses.

• The space available for diagnostics is severely limited by the TBR(Tritium Breeding Ratio) : a minimum set of systems is used to protect and control the machine. The engineering of diagnostics must be inserted in the overall design of DEMO from the Beginning due to the optimization of the space dedicated, compatible with the TBR: likely the organization of diagnostics in PORT PLUGS of ITER will NOT be used.

• The high fluence of DEMO ( 30-50 x ITER fluence ) put the other important constraint on the diagnostics: in practice the ITER diagnostics MUST BE REVISITED BECAUSE OF THE HIGH DPA IMPLIED IN DEMO OPERATIONS. • Diagnostics (nearly) feasible ( low extrapolation from ITER design and R&D needed )

Microwave ( and Far Infrared Light ) techniques Direct line-of-sight techniques (neutrons, x-rays)

Yes

No

Detailed design

Integration of diagnostics onto DEMO

Design of DEMO reactor

System conceptual design

Determination of measurement requirements & justifications

Selection of diagnostic techniques

A B

Performance Assessment Relative to Requirements

Design meets requirements?

The needs and limitations of diagnostics will have to be taken into

account in the design of Next Step/DEMO devices at a much earlier

stage than for previous devices.

Message

A Costley, A Donne, W Morris

Strategy for diagnostics&control optimization

Two phases of work can be envisaged on DEMO : I) ITER-like phase : assessment of control of Q>>10 scenario and control/training of prediction codes;

• BURN CONTROL in conditions where Palpha/Pinput ~7 is UNIQUE to DEMO

• The training of transport/prediction codes for Control will imply the use of diagnostics set similar to ITER

II) Power-plant phase : TBR >1.1 constraint , severely limits the access and minimum set of diagnostics must be used + codes

Machine Diagnostics Heating and Current Drive

JET 10 3 + ICH antennae (internal)

ITER 36 26 (includes HNB3 and LH)

DEMO 3-5 6-10

Comparison of Surface Occupation ( TBR ≥1.1)

Areas (m2)

P Thomas

NEUTRON DAMAGE on DEMO1

Outboard damage (dpa) radial profile

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

0 20 40 60 80 100 120

distance from the first wall (cm)

dam

age

(dp

a)

1 FPY

5 FPY

10 FPY

20 FPY

Manifold

BB Cooling plates

FW

Eurofer m2 in Manifold

SS316 m40 in VV

R. Villari, F. Moro

PPPT WP12-DTM04

0 40 80 120 160 200 240 280 320 360

1,0

1,2

1,4

1,6

1,8

2,0

2,22.11 MW/m

2

1.76 MW/m2

1.90 MW/m2

inboardoutboard outboard

Ne

utr

on

wa

ll lo

ad

ing

[M

W/m

2]

Poloidal angle [degree]

Poloidal profile of the neutron wall loading to the first wall of the 2006/08 DEMO.

Example of Poloidal profile of neutron wall loading

Vertical ports Can be used for diagnostics Because of: 1.Lower neutron flux( a factor 2 less with respect to equatorial ports) 2. space available.

• machine protection • Basic control • ADVANCED CONTROL (ITER-like phase)

Classification of diagnostics for DEMO

machine protection basic control advanced control (*)

disruption alpha part measurements

heat loads burn control current profile

alpha losses MHD control kinetic profiles ( pedestal)

density control ELM mitigation

plasma position Radiation control

fusion power

radiation divertor control

equilibrium

(*)Not working in power plant phase

Diagnostic systems FOR MACHINE PROTECTION

R Felton

(*) using monitors of W emission close to 5nm , containing the quasi-continuum emission W 27+ - W 35+ and spectral lines at 0.794nm emitted by W 46+

Minimum set of dia for Machine protection(R&D needed) : Magnetics (Hall sensors to be tested at high dpa>3, Low Temperature Co-fired Ceramic (LTCC)technology under test for ITER?? ) IR Cameras ( W or Mo mirrors to be tested for dpa>3) Polarimetry ( W or Mo mirrors to be tested for dpa>3) Position reflectometry ( ITER reflectometry nearly OK(?)) Fission chambers(ITER fission chambers to be qualified ) X-ray spectroscopy ( X-ray mirrors and/or policapillary lenses to be tested ) VUV and Vis spectroscopy (*)( W or Mo mirrors to be tested )

FIRST MIRROR

C Vukolov

V S Voitsenya 2013

Magnetics DEMO will definitely need steady-state measurements to compensate for drifts, ideally in-vessel.

Most promising technology is metallic Hall probes . For shape control, ITER may also well prove plasma position reflectometry is

adequate. Maintenance of the sensors and cabling should be foreseen for the high fluence

region:sensors and cabling could be replaceable with the blanket system just as ITER divertor sensors are replaceable with the divertor.

G Vayakis

I DURAN

Neutronics

Diamond detectors Candidate detector for ITER n camera: Very robust material Temperature resistant Radiation hard Fabrication CVD

G Ericsson

M Pillon(2011) , Milocco(2013)

Faraday Rotation Measurement Is Promising method in Future Reactor Due to High Resistance to Mirror Degradation ITER :Measurements of Density ( error 8%) and Temperature( error 30%) possible by polarimetry

Imazawa

POloidal POLArimetry

15 viewing chords, 119 μm K Itami

BURN CONTROL

6.214.26.2

8.007.08.0

26.391.12

26.291.0

26.391.13

2

*5

*

*2

*)/(

);1(

MIXfusion

MIX

loss

TD

TMIX

MIX

fnCP

fnCT

TnnTC

PlossPfor

ignitiontoClose

TnEIPBy

TnE

nTmWP

factordilutionC

nn

nf

VnTfCP

BURN CONTROL can be achieved by: Density Control Impurity Control Temperature Control ISOTOPIC MIX CONTROL

To control the burn the sensible parameters are : ne, fMIX and C.

%21

%5

%10

isdensityoftmeasuremenforneededaccuracythe

ne

ne

changingofypossibilittheimpliesPfusinoftoleranceA

tecnical specifications

diagnostics for

BURN CONTROL

accuracy space resolution

time resol systems

Te (bulk) 5% a/10 <100ms ECE (Polarimetry)

ne 1% a/10 <100ms polarimetry , reflectometry

impurities 10% integral <100ms VUV-Xray spectr

Zeff(line int.) <20% integral <100ms vis spectr Pfus 10% integral <100ms neutronics

confined fast ions 20% a/10 100ms NPA(*)

nD/nT 10% a/10 <100ms NPA(*)

Ti(bulk) 10% a/10 100ms neutronics ,X-ray specrometers

Diagnostics for Burn Control

Minimum set of Dia BURN CONTROL: ECE Magnetics Reflectometry Polarimetry Neutronics VUV spectroscopy Vis spectroscopy NPA (*) γ ray spectr.(*)

(*) M PETROV Poster P22 this workshop

MHD CONTROL

M de Baar

1 Applicable with some R&D

2 Good prosects of applicability

3 Applicability is challenging

4 Very limited hope for applicability

5 Not applicable

DIAGNOSTICS for Divertor Control

R Wenninger

Measurement Primary ITER diagnostic

DEMO applicability

DEMO alternatives

Main plasma Prad Bolometers 2 None

Neutron flux --> Fusion power

Neutron flux monitor, neutron flux camera 1 None

ELMs & L-H Transition Visible spectroscopy (D-alpha) 3 ECE, Reflectometry,...

Divertor erosion rate

Divertor erosion monitor (Frequency modulated LIDAR, Interferometry,...) 2-3

Total erosion Divertor erosion monitor 0 Impurity implants (???)

Divertor gas composition Residual gas analyser 1 None

Divertor gas pressure Pressure gauges 2 None

Divertor max. surface temperature & heat load IR Camera 2-3 Thermocouples (???)

Divertor position of the ionization front

Impurity Influx Monitor (Spectroscopy) 3

Target ne & Te Langmuir probes 5 Difficult

Divertor Prad Bolometers 3 None

Divertor ne & Te Interferometer, Thomson Scattering 3-4

Electron Bernstein Wave Eamission, Reflectometry (ne), Spectroscopy

Divertor protection and control demonstrated in AUG(A Kallenback (2004), Herrmann(2012)) should be considered Warning: Various effects of radiation on cabling in the divertor with high neutron fluxes.

Readiness level of neutron diagnostics for DEMO

TRL 1 Basic principles observed and reported.

TRL 2 Technology concept and/or application

formulated.

TRL 3 Analytical and experimental critical function

and/or characteristic proof-of-concept.

TRL 4 Technology basic validation in a laboratory

environment.

TRL 5 Technology basic validation in a relevant

environment.

TRL 6 Technology model or prototype

demonstration in a relevant environment.

TRL 7 Technology prototype demonstration in an

operational environment.

TRL 8 Actual Technology completed and qualified

through test and demonstration.

TRL 9 Actual Technology qualified through

successful mission operations.

System Likely

detector

TRL

(after

ITER)

Justification

Neutron flux

monitor

system

Fission

chambers

7 Used extensively on JET and other

tokamaks, planned for ITER, main

question is DT calibration accuracy

Neutron

camera

system

Scintillator

s, TOF

6 (7) Used on JET,MAST etc, planned

for ITER,

Near the plasma the system is

mostly passive i.e. limited

mechanical parts

Number of lines of sight and

detector choice are crucial to

maximise number of measurable

parameters and accuracy of

results

S Lilley

Planning of R&D for Diagnostics

The planning of R&D must take into account that i) a programme including the selection of tests of minimum set

of sensors and control schemes must be carried out on ITER , JT-60SA and other devices available before DEMO comes into operation

ii) the use of codes like METIS( J-F Artaud) , RAPTOR( F Felici) for DEMO control can be inserted in the context Of ITM ( International Tokamak Modelling) activity

iii) The activity on DEMO diagnostics can be inserted naturally inside the regular meetings of ITPA TG Diagnostics

Demo DIA MACRO-AREAS

1. Burn control : DIAGNOSTICS FOR ALPHA PARTICLES , PLASMA TEMPERATURE, FUEL MIX 2.Machine protection : disruption diagnosis and avoidance 3.TRANSPORT/simulation/control CODES AND SINTHETIC DIAGNOSTICS : examples are METIS CODE(J-F Artaud), and RAPTOR ( F Felici poster P14 ) 4.Radiation hardening of diagnostics and components

Tests on JT-60SA

K Itami

Tests on FTU

Conclusions

•DEMO diagnostics should focus on high priority parameters: diagnostics for machine protection and basic control to be useful for BURN control in long pulses.

•The space available for diagnostics is severely limited by the TBR : a minimum set of systems is used to protect and control the machine. The engineering of diagnostics must be inserted in the overall design of DEMO from the Beginning due to the optimization of the space dedicated, compatible with the TBR: likely the organization of diagnostics in PORT PLUGS of ITER will not be used.

• The high fluence of DEMO ( 30-50 x ITER ) put the other important constraint on the diagnostics: in practice all the ITER diagnostics MUST BE REVISITED BECAUSE OF THE HIGH DPA IMPLIED IN DEMO OPERATIONS. • Diagnostics feasible ( low extrapolation from ITER design and R&D needed )

Microwave ( and Far Infrared Light ) techniques Direct line-of-sight techniques (neutrons, x-rays)

Basic questions

1. Main differences between ITER and DEMO ( plasma parameters and device assembly) 2.In general : Diagnostics and Control needs for a DEMO reactor ( pulsed and Steady state) and related Technical specifications of measurements. Main criteria to be adopted . 3.Which parameters needs to be controlled : sensors and actuators 3.1.Physics constraints leading to limitations and selection of Diagnostics 3.2. Fundamental Reactor Device Engineering constraints to be taken into account leading to Diagnostics construction criteria /guidelines 4. Present status of technology and tech.readiness level classification : in practice 4.1.which systems can be built with the available technology 4.2.where a reasonable extension of the present technology can be envisaged 4.3. new concepts to be developed