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Slide 1 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
H&CD Systems and their Impact on
Scenario/Economics (Lessons learned from ITER Design)
PR Thomas
ITER Organisation, Route de Vinon sur Verdon, F13115 St Paul-lez-Durance
Grateful acknowledgements to B Beaumont, D Boilson, Federichi(F4E), T
Franke(EFDA), L Grisham(PPPL), R Hemsworth, M Henderson, M Nightingale(CCFE),
E Poli(IPP), K Sakamoto(JAEA), E Surrey(CCFE) and the ITER Heating and Current
Drive Division
The views and opinions expressed herein do not necessarily reflect those of the ITER Organization
Slide 2 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
Outline of talk
Introduction
Electron Cyclotron Heating and Current Drive
Ion Cyclotron Heating and Current Drive
(Lower Hybrid Current Drive)
Neutral Beam Heating and Current Drive
Generic technical issues
Conclusions
Slide 3 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
ITER H&CD Requirements & Wagner Report
Heating Scenario ECH (MW) NBI (MW) ICH (MW)
Baseline 20 33 20
ECH-dominated 53 0 20
100% ECH 73 0 0
No ICH 40 33 0
ECH&CD system => localized H&CD across 0.0<≤0.9 and ~6.7
MW of counter-ECCD, in the range of 0<<0.45.
Require 3000 sec with duty cycle 25%
Working Group(Chair Fritz Wagner) charged by F4E to assess
the possibility to reduce ITER costs by an evaluation of an ECH-
only or ECH-dominated heating mix and the potential extension
to DEMO of ITER H&CD.
All scenarios have major consequences on buildings, vacuum
vessel, power supplies and the safety system.
Slide 4 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
Wagner Report Findings
The heating scenario A with all three heating methods
should be maintained.
Panel commented that the findings of this Report did not
provide hoped for substantial reduction in cost.
This reflected: • Results from extensive simulations taking into account the
constraints from the core physics goals of the ITER missions
=> guarantee to pass H-mode threshold.
• Analysis of specific role of each of the heating systems and
the differences between the costs would not justify any major
change in the ITER heating mix. (ECH running costs)
If DEMO needs substantial current drive power, it will
significantly increase fusion costs if NBI cannot be used.
NBI is an important option for current drive in DEMO
because of its high current drive efficiency.
Slide 5 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
Contrast Conditions JET ITER DEMO
Machine Fusion
Power
(MW)
Fusion
Power
Density
(MW.m-3)
Shot
Duration
(s)
dpa/yr Average
neutron
fluence
(MWa/m2)
JET
16 0.16 ~1 ~0 ~0
ITER
500
300
0.5
0.3
400
3000
0.5
0.1
DEMO
2000 2.0 ~few 106 20 7.5
Step from ITER to DEMO seems to be greater than
that from JET to ITER.
Slide 6 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
Extra H&CD Requirements for DEMO
Availability
Thermodynamic
Efficiency
Net electrical power
(low Pmag and PBOP)
Physics
D Ward Limit Padd>> Pmag, PBOP
DEMO current drive efficiency ηwp.CD = 0.24-0.27
First wall surface area taken by H&CD, including
structural elements, ~ 6m2 for tritium breeding (~26m2
in ITER)
Very high availability – certainly much better than
overall system availability
Slide 7 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
• 12 Power Supplies (F4E & IN-DA)
• 24 Gyrotrons (F4E, IN-DA, JA-DA, RF-DA)
• 24 Transmission lines (USIPO)
• 4 Upper Launchers (F4E)
• 1 Equatorial Launcher (JA-DA)
• EC Main Controller (F4E)
Clash
Upper Launchers
Equatorial Launchers
Transmission Lines
Gyrotrons
Power
Supplies (not shown)
ITER ECH – as-designed system
Slide 8 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
ITER ECH – wall-plug efficiency Lower Limit Upper Limt Comment
ηtrans Pout ηtrans Pout
22kV feeds - 50.5MW 45.0MW
PSM PS 95% 48MW 97% 43.6MW Published results from TCV
Gyrotron 50% 24MW 55% 24.0MW Published results from JAEA
MOU ~95% 22.8MW 96% 23.0MW Published results from JAEA
T-line ~91.5% 20.9MW 96% 22.1MW Published results from JAEA
Launcher ~95% 19.8MW 97% 21.5MW JAEA and F4E estimate
Plasma >99.5% 19.7MW >99.5% 21.3MW Codes & Exp. results
Total 39% 19.7MW 47.5% 21.3MW
Aux. 2.5MW 2.2MW Based on JT-60U EC system
Cooling 3.0MW 1.25MW Assume 5 to 10% of
dissipated power
Total 35.2% 56.0MW 43.9% 48.5MW
“Aux.” includes body p/s, SC magnet, magnet compressor, control system and
other less significant power users. M Henderson
Slide 9 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
ITER ECH – gyrotrons
IAP RAS GYCOM INF
At 170GHz:
JA: 0.8MW/100s, 1.0MW/1hr
RU: 0.99MW/1000s, 1.2MW/100s,1.5MW/2.5s
Efficiency ~50% at each operating point above
Cost issue in Wagner study arose from comparison of capital + 10 years
operation more powerful gyrotrons
G Denisov and K Sakamoto
Slide 10 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
ITER ECH – transmission lines
Aluminium annealing begins at low
temperature. Loses 20% yield
strength at 1300/10000hrs.
Loss of strength compromises
vacuum seal and alignment.
Must remain at < 1200C
Maintain integrity at
10350/2 hours – shutter
valves at penetrations
Alignment accuracy
Building movements
challenge mode purity
requirements
Cooling water chemistry
G Hanson Dec 2013
Slide 11 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
:
- Antennas: EU DA, BTP, design under development by F4E and consortium of EU labs
- Transmission lines and matching systems: US DA, at functional specs.
- RF sources and HV Power Supplies: IN DA, at functional specs, + IO (part of HVPS).
&
Switching network
3MW test loads
ITER ICH – as-designed system
Slide 12 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
ITER ICH – antenna design
Strap Housing / Straps
HIP solution with promising
thermal / structural
performance, manufacturing
route explored, assembly
sequence developed
Faraday Screen
Square channel design
developed with supporting
modelling
4 Port Junction
Deep drilled solution with
full assembly sequence
developed
M. Shannon et al, CCFE
Rear Shield Cartridge
Extended, with now deep drilled cooling
solution developed to attenuate neutron
streaming
Slide 13 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
ITER ICH – wall-plug efficiency
Input terms (MW) Output terms (MW)
AC input power 40 Plasma launched power 20
Cooling power 1.8 Losses in cooling system 1.8
Heat load into PHTS 1.5
RF sources cooling CCWS 14.5
AC/DC converter cooling
CCWS
0.8
TL line losses CCWS 0.75
Matching losses CCWS 2
Air dissipation 0.45
Total 41.8 41.8
End stage efficiency @ 1.6 MW for various load conditions. The average values
are: 66.9% for matched case, 64% for VSWR=1.5, 56.4% for VSWR=2, and 64.5%
for VSWR=1.5 and dedicated HVPS.
Gives efficiency of 48% (20MW launched and no plasma losses)
B Beaumont
Slide 14 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
IC Antenna
ECH and ICH – port-plugs
Port plugs were conceived to permit maintenance of payloads in Hot Cell
Facility
However, 100% remote handling for insertion and removal is not likely to
be achieved – many operations will be hands-on
Sealing and alignment requirements difficult to meet
Tritium contamination/decontamination not yet fully addressed
We are struggling to meet target 100micro-Sv/hr at back of port-plug
Projected area relative to that taken by heat-flux too large for DEMO
DEMO should remove such modules to other side of blanket, at very
least, and “view” plasma through pipes – ECCD steering? Waveguide
material?
Slide 15 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
ITER ECH & ICH – windows
Outer removed
Window assembly
IC Antenna VTL
EC diamond windows
EC and IC windows serve as confinement barrier.
Safety requirement, low RF losses, thermo-mechanical
loads and radiation require extensive R&D effort
Slide 16 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
Tokamak Bldg NB Cell
Bldg 37 HV Hall
Building 34 LV Power Conversion
2 (+1) HNB + 1 DNB
NB Injectors connected
to equatorial ports 4 & 5
(& 6):
•HNB 1&2(&3) : tangential
•DNB : ~radial
Negative ion technology
Strong R&D Programme
supported by EU, JA & IN
NB – as-designed system
Slide 17 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
NB – wall-plug efficiency Extrapolation to DEMO ussing an ITER beam source with a gas neutraliser or an upgraded ion source, RF power supply and either a photon or Li neutraliser.
Gas
neutraliser
Photon
neutraliser
Photon
neutraliser
Li
neutraliser
Li
neutraliser
MW MW MW
Electrical power to the ion source. 1.6 1.2 1.2 1.2 1.2 The ion souce size is reduced as it is assumed that there are no
gaps between the aperture groups horizontally for the photon
and LI neutraliser cases, and the RF power is reduced
proportionately.
The AC to RF conversion efficiency for the ion source power
supplies is 50%.
RF power to ion source 0.8 1.0 1.0 1.3 1.0 The efficiency of the RF power supply is assumed to increase
from 50% to 80% for the photon and Li neutraliser cases.
Accelerated ion power 40.0 40.0 40.0 40.0 40.0
Accelerated, dumped electrons 0.80 0.66 0.66 0.66 0.66 The accelerated electron power is approximately proportional to
the source pressure, which is assumed to be 0.2 Pa for the
photon and Li neutraliser.
Total accelerated power 40.8 40.7 40.7 40.7 40.7
Power lost in the accelerator due to beam particle other
secondary processes
10.1 6.7 6.7 6.7 6.7 The accelerator losses are proportional to the source pressure
and the extracted ion current, and scaled from the gas
neutraliser case.
Energy recovery efficiency 0.0 0.0 80.0 0.0 80.0
DC power to accelerator 50.9 47.4 36.0 47.4 36.0
Electrical power to the accelerator. 58.2 54.1 41.1 54.1 41.1
The AC to DC conversion for the accelerator power supplies is
87.5%.
Neutral power from the neutraliser. 23.2 36.0 36.0 26.0 26.0 Neutralisation for the D2 target is assumed to be 58%, 65% with
an Li neutraliser and with a photon neutraliser it is 90%.
Neutral power after halo loss 2.0 2.0 2.0 2.0 2.0 The halo loss is taken as 2% in all cases, asuming a modified
accelerator that eliminates most of the halo.
Neutral power to DEMO without re-ionisation loss. 21.6 33.5 33.5 24.2 24.2 The geometric transmission is 95% for the core of the beamlets
for both types of injector.
Neutral power to DEMO after re-ionisation loss 20.1 32.8 32.8 23.7 23.7 In the present design the re-ionisation loss is 7%.
In upgrade the source pressure is halved and there is no
neutraliser gas, reducing the total gas influx by a factor of
approximately 5. The re-ionisation losses are proportional to the
gas influx to the injector plus the gas 0utflow from the tokamak.
The re-ionisation loss is calculated to be 2% with the photon
neutraliser and the Li neutraliser.
Injected into DEMO 20.1 32.8 32.8 23.7 23.7
R Hemsworth
Slide 18 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
NB – wall-plug efficiency
Electrical power to the residual ion
dump. 1.6 0.0 0.0 1.4 1.4 In the present injector there is additional power due to electrostatic
acceleration of ions onto the dump plates and secondary electrons
from the positive ion collection plate accelerated across the dump
channel. The high neutralisation with the photon neutraliser leads to
low, mainly negative, ion flow from the neutraliser, hence a low power
to the dump
Electrical power to the laser. 0.0 2.0 2.0 0.0 0.0 800 kW of laser power is required to inject sufficient photons into the
neutraliser. Solid state laser arrays now achieve 40% efficiency. Laser power efficiency is 40%.
Electrical power to the active
correction and compensation coils. 1.6 1.6 1.6 1.6 1.6
The AC to DC conversion efficiency
for the ACC coils power supply is
95%.
Electrical power for the cryogen
supply. 0.5 0.3 0.3 0.3 0.3 0.5 MW is estimated (RSH) as the additional power in the cryoplant
needed for the beam cryopumps.
Electrical power for the water
cooling of the beam source, and the
beamline components.
0.8 0.3 0.3 0.7 0.7 0.8 MW is estimated as the power needed for the water pumps with
the gas neutraliser. The power for the Li and photon neutralisers are
scaled as the power to DEMO/electrical power to te injector.
Total electrical power to the injector 62.6 58.3 45.3 58.0 45.0
Overall efficiency (%) 32.1 56.3 72.5 40.9 52.7
ITER design Photon neutraliser Li neutraliser (Without and with energy recovery)
R Hemsworth
Slide 19 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
NB – Cs, divergence & source brightness
Cs consumption likely to be ~0.5kg/yr at 80%
availability. (Early ELISE results encouraging – Cs
consumption less)
Migration into beam-line? Evidence conflicting
Note need in ITER for ~annual Cs oven replacement
Current drive efficiency assumes ~<5mrad divergence
ITER design – 285A/m2 deuterium. Significant
improvement would reduce the size of the nuclear
island.
Slide 20 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
ITER ECH – “Physics” CD efficiency
Ip = 9MA/ne = 0.7x1020m-3/Te0 = 27keV
• Contrast with «DEMO 1 & DEMO 2 EC» (E Poli, IPP)
modelling, where DEMO2 conditions
(R = 8.5m/Ip = 22.8MA/ne0 = 0.93x1020m-3/ Te0 = 64keV/ f = 230GHz/ flat density profile
CD(0.37) = 0.33
• This increase is presumably a result of the doubling of Te.
Slide 21 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
H&CD Current-drive efficiency
System “Physics”
current drive
efficiency CD
Wall-plug
efficiency ηwp
as per ITER
design
Product
ηwp.CD
Product
ηwp.CD with
technical
improvement
ECCD 0.15 0.44 (upper
value)
0.07 0.14 (gyrotron at
70% - K Sakamoto)
ICCD 0.3-0.4
(matching?)
0.48 0.14 - 0.19 HH FWCD
???
NBCD 0.4-0.45 0.32 0.13 – 0.14 0.22 – 0.25 (photon neutraliser)
• DEMO required current drive efficiency ηwp.CD = 0.24-0.27
EC is OK on ηwp but is struggling with CD until Te >50keV
Conventional IC not applicable and FWCD an unknown
NB OK on physics but needs photon neutraliser
Slide 22 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
DEMO– (very-)high-harmonic FWCD
Two schemes have been proposed to use fast waves for
current drive:
• High Harmonic FWCD – using folded waveguide
launcher
• Very High Harmonic FWCD – using travelling wave
launcher – see A Garofalo’s this afternoon
Both offer good current drive efficiency (CD = 0.4-0.45 for
HH FWCD) and conventional, high efficiency sources.
Both are compatible with tritium breeding requirements
HH FWCD needs to be tested somewhere. VHH FWCD will
be tested on DIIID.
Slide 23 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
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Front-end Components in ITER
IC Antenna
EC scanning mirror
NB duct liner
These components do not appear to be compatible with the
DEMO environment – concept changes needed!
Slide 24 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
Maintenance – remote handling
Connection rail
Transfer
system
Monorail
crane
Beam Line
Transporter
Beam Source
RH Equipment
Upper Port
Plug RH
Equipment Tools
Ground support
vehicle
Top lid
opening
mechanism
BSV Rear flange
opening mechanism
Have already mentioned maintenance/Remote Handling in
context of port-plugs.
NB has large RH components and has a dedicated,
overhead monorail to carry them to transfer system.
Development of this system is well advanced.
Slide 25 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
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Maintenance – T2 release/(de)contamination
This is a generic issue, whose resolution at ITER will
greatly benefit DEMO
It is clear from existing experience at JET, TFTR and tritium
labs that it can be dealt with but that mitigation by design
and by detailed development of procedures is absolutely
necessary.
RH bagging of NB source and
transfer to monorail transporter
J Graceffa
Slide 26 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
Availability
• It is my opinion that the availability of ITER H&CD
systems is essentially impossible to estimate at present.
• This will change, once production prototype gyrotrons
and NBTF are in operation. (cf JET NBI and DIIID ECH)
• Mitigation is at hand: have made allowance for 1.3MW or
more gyrotrons and H&CD will push for 3rd NB line. Will
also provide insurance in the event that H-mode
threshold is on high side.
• ICH is likely to be highly available but its usefulness will
depend on coupling – ITER-like antenna will be re-
installed on JET to test the concept thoroughly
Slide 27 2nd IAEA DEMO Workshop, Vienna December 2013 PR Thomas
© 2013, ITER Organization
IDM UID: XXXXXX
Conclusions It is obvious that the DEMO technical requirements for H&CD
are different to those of ITER
Impact of T breeding requirements
Neutron fluence
Current drive efficiency
An aggressive R&D programme should be mounted, after ITER
is in operation to develop high-power (4MW), efficient (70%)
gyrotrons and photon neutralisers for NBI.
It would be enormously helpful if a HH FWCD with a folded
waveguide launcher were mounted on an existing tokamak.
ITER will benefit DEMO in respect of stepwise
technical progress, the physics of H&CD with
a burning plasma, safety and generic
maintenance issues.
Recommended