Preparing next JET full D-T Campaign João Figueiredo EUROfusion

Comparison of Power Systems Why fusion? Most exoenergetic reaction in the known universe Highest power density per Kg Lowest emission of greenhouse gases Technically safe J. Figueiredo | ESI – Hamburg | July 2017

The fusion process Light nuclei fuse into heavier nuclei Fusion products; 14.1 MeV neutron and 3.5 MeV alpha particle J. Figueiredo | ESI – Hamburg | July 2017

Principle of Energy Production with Magnetic Fusion For the nuclei to get close enough to fuse they have to overcome the Coulomb barrier. To achieve this an alternative are hot plasmas: a plasma is a ionised gas (ions and electrons are separated) For fusion to be an energy source, a hot and dense fuel plasma must be confined in a tight volume for long times... ”Magnetic bottle” J. Figueiredo | ESI – Hamburg | July 2017

Magnetic confinement The magnetic field (in reality the magnetic pressure), represented by horizontal white lines, reduces the random motion of the particles and confines the plasma (in the direction perpendicular to the magnetic field lines). J. Figueiredo | ESI – Hamburg | July 2017

Parameters of Fusion Plasmas Magnetic fusion plasmas have temperature and pressure higher than the solar corona and temperature one order of magnitude higher than the Sun core Region of Quantum plasmas J. Figueiredo | ESI – Hamburg | July 2017

Tokamak overview Magnetic field configuration Heating schemes Fusion products. 14.1 MeV neutrons to provide the energy output. 3.5 MeV alpha particles confined to keep the plasma hot Plasma current: at present generated inductively J. Figueiredo | ESI – Hamburg | July 2017

Tokamak Plasma Overview Tokamak plasma topology The plasma has an elongated cross section to improve confinement. The divertor is the part of the device explicitly designed to cope with energy and particle exhaust. The particles follow complicated orbits.

Challenges for continuous operation Efficient reactor at high Q =Pfus/Padd relies on the optimisation of bootstrap currents (currents generated by the pressure gradients) J. Figueiredo | ESI – Hamburg | July 2017

JET ILW–Be main Wall, W in the divertor JET main parameters Major radius 3.1 m Vacuum vessel 3.96m x 2.4m Plasma volume up to about 100 m3 Plasma current up to 5 MA Toroidal field up to 4 Tesla Pulses of tens of seconds JET has some unique technical and scientific capabilities: Tritium Operation Plasma Volume and Magnetic Field to confine the alphas The same wall materials as ITER (W and Be) Mission: Mitigate ITER risks and help qualifying ITER scenarios, technologies and procedures. A scan in isotopic composition and a DT campaign are unique opportunities

Fusion power has been produced on JET 16 MW fusion power produced on JET with 25 MW external power to heat the plasma First demonstration of alpha heating Tritium technologies tested Illustrates main research thrusts J. Figueiredo | ESI – Hamburg | July 2017

JET is the best performing magnetic fusion experiment ≈30 years Measured confinement time (s) Predicted confinement time (s) Size This approach has allowed the full qualification of the baseline regime of operation of ITER: the H-mode TCV Fusion research profits from a step ladder approach based on devices of different size but similar magnetic configuration JET provides the point closest to ITER for the extrapolation of H-mode confinement J. Figueiredo | ESI – Hamburg | July 2017

Strategic Context for JET J. Paméla, Fusion Engineering Design, 2007 Coherent approach in a multi-annual “JET programme in support of ITER” based on the full exploitation of the ILW J. Figueiredo | ESI – Hamburg | July 2017

JET ITER-Like Wall New JET Capability for EP2 NBI: ~ 35MW Pellets for ELM control: 50Hz Enhanced spectroscopic coverage

New wall completely installed mainly with remote handling! Beryllium Saddle coil protection W-coated CFC Restraint Ring Protections Inconel Upper Dump Plate Mushrooms Bulk W Inner Wall Cladding Normal NBI Inner Wall GL’s Poloidal Limiters New wall completely installed mainly with remote handling! About 3.500 tile assemblies More than 2 tons of Be Inner Wall Guard Limiters Re-ionisation Protections Normal NBI IW Cladding LH + ICRH Protection Saddle Coil Protections B&C tiles Saddle Coil Protections Divertor Bulk W J. Figueiredo | ESI – Hamburg | July 2017

Installation via Remote Handling Systems J. Figueiredo | ESI – Hamburg | July 2017

Reduction in Fuel Retention with the ILW in Comparison with the CFC Wall Robust and reproducible result from gas balance studies Reduction of fuel retention by at least one order of magnitude J. Figueiredo | ESI – Hamburg | July 2017

Reduction of C content by at least one order of magnitude Reduction in impurity content with the ILW in Comparison with the CFC Wall Evolution of carbon in the plasma edge (CIII at 97.7nm) during the last campaigns with CFC walls and the ILW Reduction of C in the plasma edge: CFC vs ILW D He H D JET with ILW min. factor 10 JET with CFC Reduction of C content by at least one order of magnitude J. Figueiredo | ESI – Hamburg | July 2017

Neutral Beam Enhancement IAEA TCM 2011, San Francisco, June 20-24 Neutral Beam Enhancement NB Operating Space (D2) 24 MW limit 10 s pulse length limit 35 MW limit 20s pulse length limit New power supplies Major reconfiguration New PLC controllers Reactive Power Compensation J. Figueiredo | ESI – Hamburg | July 2017

Next DT Campaign on JET: DTE2 overview Reference DTE2: 50/50 D-T for a neutron budget of 1.7x1021 about a factor of 7 higher than DTE1 (previous main DT campaign in JET which took place in 1997) Neutron flux on the first wall up to 1013 n/s·cm2 as in ITER between the blanket and the vacuum vessel Neutron fluence on first wall up to ≈ 1015n/cm2 (≈10-6 dpa). At this fluence level, degradation of physical properties of functional materials of diagnostic relevance can be observed (although not relevant for structural materials) Unique TT campaign to complete the isotope scan (which was not granted time during DTE1) J. Figueiredo | ESI – Hamburg | July 2017

Fusion performance Ambitious Target : Pfusion ~ 15MW for 5s DTE-2 ELMY-H & Hybrid scenarios ITER scenarios – Performance projections: ELMy H-modes at 4.5 MA/3.6 T: H98~0.85-1, Zeff~2 at Q~0.16-0.2 Hybrid plasmas at 3.5 MA/(3.45 T): H98~1.2, Zeff~2 at Q~0.3-0.5 Advanced scenarios at 1.8-3.4 MA/2.7-3.5 T and q0~2 for a range of plasma parameters, e.g. and Zeff~2, projecting to Q~0.1-0.4. J. Figueiredo | ESI – Hamburg | July 2017

Last DD Campaign on JET: Performance In terms of performance of the heating systems, JET managed to achieve its target for the last campaigns. 3MA ILW (2016) (2014) We are back on the IPB98y scaling These discharges preserve the positive properties of the ILW Peak neutron rate of about 3 1016 was achieved J. Figueiredo | ESI – Hamburg | July 2017

Tritium Retention with ITER materials Be, W ~0.3% retention fraction reduction by more than one order of magnitude gas-balance & post-mortem analyses Co-deposition in W-Be layers (2/3) dominates over implantation (1/3) Fuel analysis in narrow gaps Sectioning of beryllium limiters JET–ILW: 170 000 castellations L~ 7325 m, S~ 88m2 ! Fuel retention at the very entrance (<1mm) of grooves no transport deeper into gaps in agreement with modelling Narrow gaps (0.4 mm) minimise retention ITER predictions on basis of JET-ILW plasmas (C30C): 3000 – 20 000 discharges

Comprehensive Dust Particles Survey Mobilisable Dust two orders of magnitude less than JET C-Wall 1.82g Dust collected: vacuum cleaning sticky pad Source Predominantly from W-coated tiles Be melting from disruptions Only 50-70mg from Be co-deposit Unique and reassuring data set for ITER safety Safety issue

DT technical rehearsal Additional technical and safety requirements in tritium operation: Tritium is stored in uranium beds and will be supplied by the tritium plant to one or two neutral beam boxes and five new tritium introduction modules. The torus hall atmosphere will be under depression (to limit the spread of tritium in case of accidental tritium release) and is depleted to 15% oxygen level (fire suppression). Restricted access to key operational areas of the JET building (neutron activation) Tightened access restrictions will be applied to computer networks. All cryo-pumps will be regenerated daily (tritium inventory, flammable gas limit) Additional tritium operational procedures are used in the JET and the tritium plant control rooms. Fuel cycle at JET J. Figueiredo | ESI – Hamburg | July 2017

JET Diagnostic Enhancement Projects Operation support diagnostics DT compatible camera views project (Itziar Balboa CCFE) Upgrade Charge Exchange for Ti (Nick Hawkes CCFE) Instabilities Diagnostics Correlation and Doppler Reflectometer project (Antonio Silva IST) Upgrade of the JET TAE system (Patrick Blanchard CRPP) Neutron Diagnostics JET Neutron Camera Upgrade project (Daniele Marocco ENEA) Vertical Neutron Spectrometer project (Francesco Belli ENEA) Gamma Diagnostics Upgrade of the JET Gamma Ray Camera (Marco Tardocchi CNR) JET Horizontal Gamma-Ray Spectrometer Upgrade for the alpha-Particle Diagnostic during the DT Campaign (Teddy Craciunescu IAP) Fast Ion Diagnostic Upgrade of the scintillator based Fast-Ion Loss Detector (FILD) at JET (Manuel García-Muñoz CIEMAT) J. Figueiredo | ESI – Hamburg | July 2017

All invited to participate!!! Summary On the route to DTE2 There is a coherent scientific and technologic development programme The recent results support the ambitious but realistic goals Diagnostics are adequate to support the ambitious scientific programme Many more activities will be carried out during DTE2 All invited to participate!!! 27