Taming the Plasma Material Interface Workshop. Internal Components Panel

Transcription

1 Taming the Plasma Material Interface Workshop Internal Components Panel Presented by Richard W. Callis UCLA

2 Outline What is an Internal Component (IC) What-Who is the IC Panel What is it to do? How is it to do it? What are the Gaps & Issues relative to each IC How are Gaps & Issues filled/resolved What is the method of developing a progressively better understanding IC Matrix Research Themes

3 What is an Internal Component? In general Internal Components (ICs) are the structures or subsystems just behind the First Wall and inside the envelope of the Vacuum Vessel. ICs are not Shield Blankets, PFCs or Divertors Internal Components are: The front end of Diagnostics RF antennas Microwave launchers Control & stabilizing coils Other?

4 What-Who is the IC Panel? The Internal Component Panel is part of the Plasma- Material Interface Theme, and is charged to detail the gaps and issues that need to be resolved prior to proceeding to DEMO. And to identify Research Thrusts that can be executed to achieve resolution of technology and scientific issues. The Internal Component Panel membership is: Rich Callis - Chair David Rasmussen Randy Wilson Jim Leuer Jim Irby Tony Peebles John Caughman Dennis Whyte Tom Jarboe lance Sneed GA ORNL PPPL GA MIT UCLA ORNL MIT UWash ORNL

5 How Does the IC Panel Members Perform Their Assignment Starting with the Priorities, Gaps and Opportunities Panel Report ( Greenwald Report ) identify the internal components needed for DEMO and what gaps must be addressed over the next 20 years. Refine and expand the details of the gaps from personal knowledge and/or from knowledge collected from colleagues White papers are used as a useful tool to obtain community input Identify processes by which the gaps can be resolved, using a graded approach Simple or near-term resolution areas first, followed by more complex or demanding areas Generally there is a cost association, with the simple tasks being less costly and the more complex or demanding having a higher cost Group common tasks or components into generalized research thrusts Condense and organize this information into a concise Matrix Develop a list of Research Thrusts

6 What are the Gaps & Issues relative to each IC

7 Diagnostics will be Severely Challenged in the Burning Plasma Era of Fusion Energy Research Increased measurement capabilities are needed to make significant advances in physics understanding and operational control. e.g. Whole array of profile measurements are needed to be available between discharges including q-profile (MSE EFIT), ion and electron temperature, electron density, etc. Broad range of turbulence and MHD diagnostics are needed to cover spatial scales from tens of centimeters down to millimeters. Presently 2D measurements are available, some future needs may require 3D capability However, it is clear that if existing diagnostic techniques were simply transferred to ITER or to DEMO measurement capability would be significantly compromised and availability potentially reduced.

8 Measurement Gaps continued Relativistic effects (assuming Te0 ~25keV) will degrade the spatial resolution of electron temperature measurement using electron cyclotron emission (ECE) technique. There is a significant concern regarding a broad array of existing optical diagnostic techniques such as Thomson scattering, charge exchange recombination spectroscopy, motional Stark effect, etc. Maintenance of the optical quality of mirrors, polarizers, windows, etc. located close to a burning plasma environment represents a significant and perhaps overwhelming challenge to overcome. In addition, the bremsstrahlung background emission will be far greater than observed in current devices and will potentially limit signal to noise. It seems likely that availability/accuracy of such visible diagnostics will be compromised in the ITER environment, especially during long pulse (~1000s) exposure to high heat and neutron loads. Projections to DEMO are even more pessimistic and would lead to further deterioration in reliability, availability and measurement accuracy. New diagnostic method which are neutron and high heat flux compatible need to be developed and validated. Diagnostics on ITER are a good start but not sufficient for DEMO

9 Measurement Gaps continued A new set of Engineering Instrumentation diagnostics need to be developed Monitor performance of In-vessel components Temperature sensors Pressure Water flow/level Acoustics Vibration

10 RF Techniques for Plasma Heating, Current Profile Control, Rotation Control, MHD Stability Control for DEMO Faces Significant Challenges In order to optimize the application of rf power to heat or drive current in DEMO a better understanding of RF-Plasma interaction is needed Uncertainties lie in the interaction between the rf waves and the core plasma. Additional difficulties lies in the interaction of the rf waves and launchers with the scrape-off plasma. Large amount of power can be deposited into thin sheaths in the SOL Modification of the plasma pedestal maybe incompatible with reactor requirements RF launchers require significant amount of space penetrating the breeding blanket. This displaces T breeding volume, and adds nuclear and radiation heat loads to the antenna structure Requires antenna to have high power density levels (arcing concern) The science basis for rf breakdown in the presence of plasmas is insubstantial

11 RF Launchers continued For DEMO the RF Launchers will be required to operate at >700 C using the same cooling technology chosen for the blankets. This technology has yet to be proven. The rf antennas will have to be fabricated from materials compatible with the neutron environment as well as being able to support efficiently the rf waves This technology has yet to be proven. Impurity generation from plasma interaction with the RF launchers is a concern. The present use of Boronization for impurity minimization is not functional in steady state operation. RF launchers have delicate components at or near the plasma surface which may not be able to withstand the harsh environment Off-normal events impose additional constraints ITER LH Launcher

12 Present Designs of Microwave Antennas Have Components Close to the Plasma Edge Structures of the microwave launches must meet the criteria of other plasma facing components. ~1-10 MW/m 2 heat and neutron fluxes Acceptable levels of impurity production Subjected to the whole host of off-normal events Survivability of steering mirrors a concern In addition the microwave components have to support intense levels of electromagnetic fields ~10-100kV/m Reflective surfaces (mirrors) need to maintain high conductivity to minimize resistive 200 GHz the skin depth of copper is only 0.15 micron Copper conductivity at 700 C is 28% of room temp copper Neutron fluxes degrade copper s conductivity Bonding of high conductivity metals to neutron compatible material has to be developed ITER ECRF Upper Launcher

13 Plasma Edge and Stability Control May Require Coils within the Vacuum Vessel Control coils are more effective the closer they are to the plasma surface. However, high neutron fluences impacts the choice and use of high conductivity metals Metals lose conductivity under neutron exposure Metals are embrittled from neutron exposure Nuclear heating adds to the heat load needing removal Shielding of coils to reduce neutron exposure requires higher coil currents to create the effect of a coil near the SOL Resulting in higher mechanical loads and increased cooling requirements High neutron fluences may limit the choice of insulating material Coils may experience high electromagnetic forces from disruptions and VDEs Coils located behind shield blocks have severe remote maintenance challenges ITER In Vessel Coils Control and stability coils planned for ITER

14 There are Several Research Topics Which are Common to All Internal Components Materials All internal components have to withstand the same environmental hardships as PFC, Shield Modules, and Divertors, as well as those imposed by their special functions. Neutron exposure, plasma radiation fluence, off-normal events, etc. To satisfy the special requirements of the internal components it is expected that layered materials will have to be developed, with the exterior layer meeting the requirements of the internal component and the base layer meeting the requirements of the PFCs and Shield Modules. These layered materials need to be developed and validated Because of the cross-cutting nature of material research the IC Panel has a material expert.

15 Qualification of Nuclear Grade Components is Another Cross-Cutting Research Topic The licensing of DEMO will require a high level of documentation that components can meet all the safety requirements and has demonstrated effective reliability and maintainability. Materials will need to be prequalified for use in an neutron environment Validation of theory and modeling on test stands Validation of system design and performance on an operating device (most likely non-nuclear) Validation of performance under high neutron and heat fluences Accumulation of operational data for RAMI classification Demonstrated high availability using Remote Maintenance is essential Continuous operation of two weeks to a month at a time Availability of 20% to 50% must be achievable Component replacement with short down time (mean-time-to repair) Full reparatory of specialized remote handling tools and end-effectors developed and available Demonstrated ability of in vessel inspection Erosion evaluation, leak detection, metrology, etc.

16 How Gaps & Issues Filled/Resolved How the Kernel of Research Thrusts are Germinated

17 The Gaps in Internal Component Technology are Large and will Take an Integrated Program to be Successfully Closed All of the internal components to be used in DEMO must pass through a rigorous development cycle A progressive research plan was proposed and a matrix was established. Physics, Theory & Modeling Technology Development Existing/Upgraded/New Test Stands Existing/Upgraded/New Non-DT Confinement Facilities New DT Confinement Facilities

18 ReNeW Internal Component Panel Gaps & Issues Matrix Internal Components Gaps & Issues and the Processes Needed to Develop Understanding & Resolution DRAFT 3 2/24/09 Gaps & Issues by Topic Area Physics. Theory & Modeling Technology Development Existing/Upgraded/New Existing/Upgraded/New Test Stands Non-DT Confinement Facilities New DT Confinement Facilities Measurement Reliable and verified techniques for: Develop/extrapolate/innovate new concept Validate techniques for predicting Develop and employ diagnostics for low- Test diagnostics components in a Adequacy of measurements predicting particle, heat, and neutron Qualify structural, shield and coating particle, heat, and neutron fluxes on Upgrade the diagnostics for ITER nuclear environment Compatibility in nuclear environment fluxes on passive components in realistic material with which to construct internal passive components (e.g. mirrors, sensors, Test nuclear-capable diagnostics on Employ diagnostics on CTF RAMI geometry in both normal and off-normal Diagnostic components (e.g. mirrors, tec.) in realistic geometry in both normal ITER Use long-pulse facilities to develop and Integrated long pulse tests of innovative Innovation operating conditions. sensors, tec.), including joining/bonding and off normal operating conditions test in-situ approaches and procedures for approaches Improve predictive capability to reduce technologies. Tests of coating techniques and In-situ tests of material surface dynamic Test nuclear-capable diagnostics on nonnuclear measurement requirements advanced refractory alloys and metal response facilities RF Antennas (ICRF, LH) Reliable and verified techniques for: Develop/extrapolate/innovate new concepts (SOL work needed for this step) Compatibility with cw high heat computing self-consistent heat and Compatibility in nuclear particle fluxes to high-power, energized Low impurity generation components which interact with and alter Sufficient EM-plasma coupling without arcing RAMI Innovation the edge plasma. improved models of RF wave * Computing all wave processes that can lead to edge losses in SOL doping SOL Microwave launchers Reliable and verified techniques for: Develop/extrapolate/innovate new concept Validate techniques for computing Compatibility with cw high heat computing self-consistent heat and Qualify structural, shield and coating heating performance and self-consistent loads Compatibility in nuclear particle fluxes to high-power, energized material with which to construct heat and particle fluxes to high-power, environment components which interact with and alter Microwave Antennas, including energized Microwave Launchers, which Low impurity generation the edge plasma. joining/bonding technologies. interact with and alter the edge plasma. Sufficient EM-plasma coupling without arcing RAMI Innovation Modeling and development of new materials Qualify structural, shield and coating material with which to construct RF Antennas, including joining/bonding technologies. Modeling and development of new materials Tests of coating techniques and advanced refractory alloys and metal Tests of coating techniques and advanced refractory alloys and metal Validate techniques for computing heating performance and self-consistent heat and particle fluxes to high-power, energized RF Antenna, which interact with and alter the edge plasma. In-situ tests of material surface dynamic response * Validate edge loss processes in existing devices and determine power flow in the In-situ tests of material surface dynamic response Test nuclear-capable RF Antennas on non-nuclear facilities Test nuclear-capable Microwave Launchers on non-nuclear facilities Test RF Antennas in a nuclear environment Validate nuclear capable RF Antennas on CTF Integrated long pulse tests of innovative approaches Test Microwave launchers in a nuclear environment Validate nuclear capable Microwave Launchers on CTF Integrated long pulse tests of innovative approaches Control Coils Reliable and verified techniques for: Develop/extrapolate/innovate new concept tests of new solid materials Compatibility in nuclear environment Predicting heat, and neutron fluxes on Qualify structural material with which RAMI Innovation passive components in realistic geometry in both normal and off-normal operating to construct internal Control Coils, including joining/bonding technologies. Cross-Cutting Topics Materials conditions. Modeling and development of new materials Modeling and development of new materials (linked with HFP MS area) Modeling and development of coatings on nutronic compatible materials that can support EM waves Predicting lifetime capability of EM coatings on launchers and mirrors under both normal and off-normal operating conditions Tests of coating techniques and advanced refractory alloys and metal doping Tests of coating techniques and advanced refractory alloys and metal Qualify structural, shield and coating material with which to construct EM Antennas and mirrors, including joining/bonding technologies. Qualify structural material with which to construct internal Control Coils, including joining/bonding technologies. tests of new solid materials Tests of heat extraction using gas or liquid metals Test nuclear-capable Control Coils on non-nuclear facilities Test internal components fabricated from nuclear-capable materials under reactor grade plasma conditions Validate nuclear capable Control Coils on CTF Integrated long pulse tests of innovative approaches

19 Example of a Gap & Issue Topic RF Antennas (ICRF, LH)* Compatibility with cw high heat loads Compatibility in nuclear environment Low impurity generation Sufficient EM-plasma coupling without arcing RAMI Innovation * Primarily extracted from Priorities, Gaps and Opportunities Report (Greenwald Report)

20 Example of a Research Area Physics. Theory & Modeling Reliable and verified techniques for: Computing self-consistent heat and particle fluxes to high-power, energized components which interact with and alter the edge plasma. Improved models of RF wave propagation from antenna through the plasma edge Computing all wave processes that can lead to edge losses in SOL

21 Technology Development Modeling and development of new materials Develop/extrapolate/innovate new concepts (SOL work needed for this step) Qualify structural, shield and coating material with which to construct RF Antennas, including joining/bonding technologies. Tests of coating techniques and advanced refractory alloys and metal doping

22 Existing/Upgraded/New Test Stands Validate techniques for computing heating performance and self-consistent heat and particle fluxes to high-power, energized RF Antenna, which interact with and alter the edge plasma. In-situ tests of material surface dynamic response Validate edge loss processes in existing devices and determine power flow in the SOL

23 Existing/Upgraded/New Non-DT Confinement Facilities Test nuclear-capable RF Antennas on nonnuclear facilities

24 New DT Confinement Facilities Test RF Antennas in a nuclear environment Validate nuclear capable RF Antennas on CTF Integrated long pulse tests of innovative approaches

25 Research Thrusts

26 The IC Panel has Identified Several Candidate Research Thrusts 1. RF Sheath & near field modeling 2. Effects of neutrons & T retention on antenna materials 3. Use magnetized plasma long pulse based RF test stands to validate antenna concepts and performance 4. Develop antenna/launcher/mirror concepts using nuclear grade materials in a high heat environment 5. Perform integrated antenna testing on non-nuclear confinement devices 6. Perform integrated engineering validation (RAMI) on a CTF device 7. Develop innovative diagnostics suitable for a neutron environment 8. Validate diagnostic performance on non-nuclear confinement devices 9. Small Medium Large Very rough range: Small $2-3 M, Medium $10-30 M, Large ~$100M per year

27 The Three Keys to Success for Fusion Energy INNOVATION INNOVATION INNOVATION

28 The Three Keys to Success for Fusion Energy INNOVATION MATERIALS INNOVATION DIAGNOSTICS INNOVATION RF ANTENNAS & LAUNCHERS