H&CD Systems and their Impact on Scenario/Economics (Lessons learned from ITER Design)

Transcription

1 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 1

2 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 2

3 ITER H&CD Requirements & Wagner Report Heating Scenario ECH (MW) NBI (MW) ICH (MW) Baseline ECH-dominated % ECH No ICH 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 ECHonly 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 3

4 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 4

5 Contrast Conditions JET ITER DEMO Machine Fusion Power (MW) Fusion Power Density (MW.m -3 ) Shot Duration (s) dpa/yr Average neutron fluence (MWa/m 2 ) JET ~1 ~0 ~0 ITER DEMO ~few Step from ITER to DEMO seems to be greater than that from JET to ITER. Slide 5

6 Extra H&CD Requirements for DEMO D Ward Availability Physics Limit P add >> P mag, P BOP Thermodynamic Efficiency Net electrical power (low P mag and P BOP ) DEMO current drive efficiency η wp. CD = First wall surface area taken by H&CD, including structural elements, ~ 6m 2 for tritium breeding (~26m 2 in ITER) Very high availability certainly much better than overall system availability Slide 6

7 ITER ECH as-designed system 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) Gyrotrons Transmission Lines Equatorial Launchers Upper Launchers Clash Power Supplies (not shown) Slide 7

8 ITER ECH wall-plug efficiency Lower Limit Upper Limt Comment η trans P out η trans P out 22kV feeds MW 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 8

9 ITER ECH gyrotrons G Denisov and K Sakamoto 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 Slide 9

10 ITER ECH transmission lines Aluminium annealing begins at low temperature. Loses 20% yield strength at /10000hrs. Loss of strength compromises vacuum seal and alignment. Must remain at < C G Hanson Dec 2013 Maintain integrity at /2 hours shutter valves at penetrations Alignment accuracy Building movements challenge mode purity requirements Cooling water chemistry Slide 10

11 ITER ICH as-designed system Switching network 3MW test loads & : - 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). Slide 11

12 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 ITER ICH antenna design 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 12

13 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 0.8 CCWS TL line losses CCWS 0.75 Matching losses CCWS 2 Air dissipation 0.45 Total B Beaumont Gives efficiency of 48% (20MW launched and no plasma losses) End stage 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. Slide 13

14 ECH and ICH port-plugs IC Antenna 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 14

15 ITER ECH & ICH windows IC Antenna VTL Window assembly EC diamond windows Outer removed EC and IC windows serve as confinement barrier. Safety requirement, low RF losses, thermo-mechanical loads and radiation require extensive R&D effort Slide 15

16 NB as-designed system Tokamak Bldg NB Cell Building 34 LV Power Conversion NB Injectors connected to equatorial ports 4 & 5 (& 6): HNB 1&2(&3) : tangential DNB : ~radial 2 (+1) HNB + 1 DNB Bldg 37 HV Hall Negative ion technology Strong R&D Programme supported by EU, JA & IN Slide 16

17 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 Photon Photon Li Li neutraliser neutraliser neutraliser neutraliser neutraliser MW MW MW Electrical power to the ion source The ion souce size is reduced as it is assumed that there are no The AC to RF conversion efficiency for the ion source power supplies is 50%. gaps between the aperture groups horizontally for the photon and LI neutraliser cases, and the RF power is reduced proportionately. RF power to ion source 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 Accelerated, dumped electrons 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 Power lost in the accelerator due to beam particle other secondary processes Energy recovery efficiency DC power to accelerator Electrical power to the accelerator The AC to DC conversion for the accelerator power supplies is 87.5% The accelerator losses are proportional to the source pressure and the extracted ion current, and scaled from the gas neutraliser case. Neutral power from the neutraliser 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 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 The geometric transmission is 95% for the core of the beamlets for both types of injector. Neutral power to DEMO after re-ionisation loss 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. R Hemsworth Injected into DEMO Slide 17

18 NB wall-plug efficiency Electrical power to the residual ion dump. 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. Laser power efficiency is 40% kw of laser power is required to inject sufficient photons into the 0.0 neutraliser. Solid state laser arrays now achieve 40% efficiency Electrical power to the active correction and compensation coils. The AC to DC conversion efficiency for the ACC coils power supply is 95%. Electrical power for the cryogen supply. Electrical power for the water cooling of the beam source, and the beamline components. Total electrical power to the injector Overall efficiency (%) MW is estimated (RSH) as the additional power in the cryoplant needed for the beam cryopumps. 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. R Hemsworth ITER design Photon neutraliser Li neutraliser (Without and with energy recovery) Slide 18

19 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/m 2 deuterium. Significant improvement would reduce the size of the nuclear island. Slide 19

20 ITER ECH Physics CD efficiency I p = 9MA/n e = 0.7x10 20 m -3 /T e0 = 27keV Contrast with «DEMO 1 & DEMO 2 EC» (E Poli, IPP) modelling, where DEMO2 conditions (R = 8.5m/I p = 22.8MA/n e0 = 0.93x10 20 m -3 / T e0 = 64keV/ f = 230GHz/ flat density profile CD (0.37) = 0.33 This increase is presumably a result of the doubling of T e. Slide 20

21 H&CD Current-drive efficiency DEMO required current drive efficiency η wp. CD = System Physics current drive efficiency CD Wall-plug efficiency η wp as per ITER design ECCD (upper value) ICCD (matching?) Product η wp. CD Product η wp. CD with technical improvement (gyrotron at 70% - K Sakamoto) HH FWCD??? NBCD (photon neutraliser) EC is OK on η wp but is struggling with CD until T e >50keV Conventional IC not applicable and FWCD an unknown NB OK on physics but needs photon neutraliser Slide 21

22 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 = 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 22

23 Front-end Components in ITER EC scanning mirror IC Antenna NB duct liner These components do not appear to be compatible with the DEMO environment concept changes needed! Slide 23

24 Maintenance remote handling Monorail crane Tools Beam Line Transporter Upper Port Plug RH Equipment Top lid opening mechanism Connection rail Transfer system Ground support vehicle Beam Source RH Equipment 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 24

25 Maintenance T 2 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 25

26 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 3 rd 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 reinstalled on JET to test the concept thoroughly Slide 26

27 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. Slide 27

28 DEMO Cockpit? Cockpit of Shuttle Atlantis Slide 28