Research Needs for Magnetic Fusion Energy Sciences - US Burning ...

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Materials and Components: Fuel Cycle: RaMi: surface heating tritium breeding ratio Radiation dose nuclear heating burn fraction component life temperatures t tie-up in components Failure modes, mtbF temperature gradients vacuum pumping maintenance processes mechanical stress t control and recovery availability Thermal stress Processing diagnostics and inspection Response to disruptions Fuel injection mean time to repair/replace effects of neutron damage t accountability transmutation t containment Gas production Power Extraction and Conversion: Safety and Environment: Fusion power activation Plasma physics 358 integrated System Model: surface & nuclear heating source terms Physics and eng constraints duty cycle accident scenarios capital and operating costs coolant flow in b field t inventory Financial parameters conversion efficiency Radwaste level Plant layout Plasma heating Recycling and free release aspects from other lists Recirculating power licensing net power output Table 1. Major systems design aspects and processes that must be simulated.
Thrust 16: Develop the spherical torus to advance fusion nuclear science The spherical torus (st) is a low aspect ratio (low-a) tokamak that offers unique physical properties due to its very strong magnetic curvature and compact geometry. This configuration delivers high plasma pressure relative to the external magnetic pressure, and strongly affects plasma stability and confinement. it offers the promise of simple magnet design, reduced size, cost, and ease of maintainability. The st program has made substantial progress. non-solenoidal startup currents have reached 25% of required initiation levels. a strong favorable dependence of plasma thermal confinement on magnetic field was found. a five-fold increase in electron confinement was demonstrated in a small device with liquid metal walls. stability needed for a component testing device was shown for several current relaxation times, with a majority of the current provided noninductively. The st program is now poised to generate the knowledge base to confidently construct and operate a low-a Fusion nuclear science and technology (Fnst) component testing device, and to aggressively pursue improvements to advance the st for energy production. Key issues: • The st has little room for a central solenoid to produce and drive plasma current. Can plasma current be initiated and raised to high values without a solenoid? • The compact geometry of the st increases the heat loading to the wall. Can plasma exhaust power be effectively dissipated in the ST? • The st energy confinement improves faster with magnetic field and plasma temperature than at high aspect ratio. Can predictive models for ST confinement be developed and validated? • The broad current profiles and near-spherical geometry of the st strongly affect stability. Can stable and continuous operation be produced at low aspect ratio? • The lower magnetic field and enhanced energetic particle drive of the st may challenge the sustainment of high plasma current. What are viable means to maintain the current and control the plasma profiles in the ST? • The compact geometry of the st precludes the use of shielded superconducting magnets. Can suitable magnets be developed for ST applications? Proposed actions: • exploit and understand magnetic turbulence, electromagnetic waves, and energetic particles for megampere plasma current formation and ramp-up. • develop innovative magnetic geometries and first-wall solutions such as liquid metals to accommodate multi-megawatt per square meter heat loads. • Utilize upgraded facilities to increase plasma temperature and magnetic field to test the understanding of st confinement and stability at fusion-relevant parameters. • implement and understand active and passive control techniques to enable long-pulse disruption-free operation in plasmas with very broad current profiles. 359
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Research Needs for Magnetic Fusion
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Research Needs for Magnetic Fusion
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ExEcutivE SuMMaRy nuclear fusion
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Magnetic confinement magnetic confi
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The thrusts span a wide range of si
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eactor, most heat comes from fusion
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thrust 18: achieve high-performance
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confinement is measured by the so-c
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PART I: ISSUES AND RESEARCH REQUIRE
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ReneW Organization: Themes The stru
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22 Table 1. ReNeW Thrusts Address R
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ON PREVIOUS PAGE Nonlinear simulati
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extended operation phase. The optim
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Figure 2. Alpha particles can cause
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Figure 3. Spectrogram of the time-v
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Do the alpha particles couple to th
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• improved understanding of the e
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most relevant to iteR. Recent obser
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H-mode access: access to the h-mode
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although present-day devices have m
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estimates indicate that it will be
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can enter the plasma core and dimin
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ent drive alone cannot account for
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Figure 10. Control involves the ele
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to operation of iteR. solutions for
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• identification and stabilizatio
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Disruption prediction accurate pred
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Figure 12. The application of non-a
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ion losses, a quantitative predicti
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due to incompatibility of the measu
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agnostic measurements of critical p
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quires assessment of when potential
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suggesTions for furTher reading 1.
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miTigaTing TransienT eVenTs in a se
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ON PREVIOUS PAGE Nonlinear simulati
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increasing power density and pulse
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of recent accomplishments that have
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ity limits have been maintained. in
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highly risky in such an environment
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proximity-coil-based magnetics is ~
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will dominate the external sources
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The barrier gradient is generally l
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interaction with plasma boundary an
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itER-at aRiES-i aRiES-at b n (%) 3.
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and morphology, are needed. new mea
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field and temperature fluctuations
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large-scale process control problem
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tics. integrated control methods fo
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ing and design include computationa
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dated in the corresponding structur
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These requirements are applicable t
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• assess computationally, on test
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Research Requirements for Electron
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the launcher design is partly “tr
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tunities and goals for a few of the
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front layers of the field magnets c
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R&D Strategy a number of critical t
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formance burning plasmas are covere
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CreaTing prediCTaBle, high-performa
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magneTs JosePh mineRvini, massachus
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ON PREVIOUS PAGE Design of the ITER
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to stabilize deleterious plasma mod
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longer than the (solid) thermal equ
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Promising new ideas have been devel
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to handle 10 mW/m 2 , and elms with
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• liquid surface PFc operation in
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integrated effort that includes fun
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Taming The plasma-maTerial inTerfaC
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138
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ON PREVIOUS PAGE Design of an ITER
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trons in the breeding blanket. Thes
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Safety and Environment • developm
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plasma and gas to the scrape-off la
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gaps: need to select and test the t
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• neutron and other radiation tra
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emphasis on modeling and expertise
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gap: Current understanding of stren
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Research needs critical research ne
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• Proposing integrated safety des
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• techniques and instruments to a
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Qualifying DEMO Components Possible
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• developing the design of an eff
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harnessing fusion power Theme memBe
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168
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ON PREVIOUS PAGE Reconstruction of
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Figure 1. Configuration space for t
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of 40%.) localized instabilities (t
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• Reduction of spheromak magnetic
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ment, but also micro- and macro-ins
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esearch requirements • evaluate t
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the banana regime, low turbulent tr
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in stellarator discharges with ohmi
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• investigate how demountable coi
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tion using a central solenoid is al
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functions, edge flows, and edge neu
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Development of predictive capabilit
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Edge localized modes (ELMs): edge l
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theory predictions for alfvén inst
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coils, to permit replacement of the
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stand the relative roles of long-to
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Table 1. 202
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primarily electrostatic, in the cas
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to be important in present experime
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PLaSMa bOunDaRy intERaCtiOnS The ex
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calized field errors that can cause
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needed Theory, Computation, Modelin
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Scientific Issues and research requ
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esearch requirements new facilities
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small, concept exploration experime
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tRanSPORt: DEtERMinE unDERLying tRa
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esearch requirements analysis of ne
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nEEDED FaCiLitiES nEEDED tHEORy, CO
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connections Between Research Requir
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opTimizing The magneTiC ConfiguraTi
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Proposed actions: • Prioritize bu
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3) as planning matures for the rese
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that have high impact, that benefit
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could have an impact on the identif
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The Us fusion program is well posit
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Mitigation of disruptions in the ev
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elevant plasmas for very long pulse
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and stability, and mitigation requi
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• control alpha heating feedback
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heavy ion beam probes (already in u
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alpha particles (ash removal). mode
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• determine minimum heating power
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Research should focus on developing
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estal structure need to be coupled
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• sufficient heating with little
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Proposed actions: Short-term: begin
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Demonstrate active control of the p
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Demonstrate burn control and contro
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Develop the means for and demonstra
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Medium-term: Test and optimize full
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• Recruit, train and support dedi
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With this information in hand, phys
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to carry out the validation program
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and new devices could be designed w
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• high-field sc magnets for stead
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Element 2 — High current conducto
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Element 7 — integration of conduc
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many other scientific fields are be
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• based on these assessments, pro
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systems include neutral beams, ion
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The Us d-t facility, studied in 1b,
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300
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• design and implement innovation
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the controlling instabilities and s
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cross-field transport in the pedest
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Page 314 and 315: • build large-size test stands wh
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Page 328 and 329: The plasma facing components in a d
Page 330 and 331: to demonstrate that steady and tran
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Page 336 and 337: introduction harnessing fusion powe
Page 338 and 339: each Thrust 13 element includes the
Page 340 and 341: Figure 3. System concept for perfor
Page 342 and 343: equirements. Understanding the fuel
Page 344 and 345: • Use a combination of existing a
Page 346 and 347: chemical interactions between the s
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Page 354 and 355: evaluate, through advanced design a
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Page 358 and 359: 3. Computational analysis managemen
Page 362 and 363: • employ energetic particle beams
Page 364 and 365: • develop and validate theoretica
Page 366 and 367: • develop new diagnostics for int
Page 368 and 369: • increase sustained noninductive
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Page 372 and 373: Proposed actions: 1. conduct two qu
Page 374 and 375: The key areas in which new knowledg
Page 376 and 377: • exploration of high-temperature
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Page 382 and 383: • study FRc stability at small io
Page 384 and 385: techniques for integrated data anal
Page 386 and 387: 4. based on the outcome of actions
Page 388 and 389: 2. With information from action 1,
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Page 392 and 393: aCROnyMS anD abbREViatiOnS (continu
Page 398 and 399: aPPENdix c: tHEME WoRKSHoPS tHEME W
Page 400 and 401: 14. d.l. humphreys, Active Realtime
Page 402 and 403: tHEME 2: CREating PREDiCtabLE HigH-
Page 404 and 405: 43. t.W. Petrie, White Paper: Some
Page 406 and 407: tHEME 3: taMing tHE PLaSMa MatERiaL
Page 408 and 409: 37. e.J. strait, J.c. Wesley, m.J.
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20. s.a. maloy and e. Pitcher, Fusi
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tHEME 5: OPtiMizing tHE MagnEtiC CO
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39. P.W. terry, a. boozer, J.s. sar
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don coRRell, lawrence livermore nat
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GeoRGe mckee, University of Wiscons
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tony tayloR, General atomics RichaR
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