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

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many other scientific fields are beginning to develop hts conductors for a variety of magnet applications, including very high field insert coils (> 25 tesla) for nuclear magnetic resonance magnets, magnetic resonance imaging magnets for diagnostic imaging and functional magnetic resonance imaging, high field, cryogen-free laboratory magnets, and possibly electric utility applications. These other applications may benefit from hts magnet technology advances achieved under the fusion magnet program. conversely, technology developments made for these other areas may be adapted to improve fusion magnet performance. Thus, government and industrial resources applied to hts technology may have synergistic effects, while spreading costs and risks among different agencies and projects. 292
Thrust 8: Understand the highly integrated dynamics of dominantly self-heated and self-sustained burning plasmas This Thrust explores the challenging demo plasma regime in which plasma self-heating (P alpha ) dominates over external heating sources (P input ), the plasma’s self-generated current dominates over external current drive, the plasma pressure is high, and the plasma radiates a significant fraction of its power. in this high fusion-gain regime Q ≥ 20 (Q = P total/P input , where P total includes the energy carried by fusion neutrons) , i.e., P alpha ≥ 4 P input , the temperature and pressure profiles are set by the plasma self-heating and underlying transport processes. The transport of energy, particles, momentum, and current, and magnetohydrodynamic (mhd) processes become strongly coupled in this regime, and the plasma reaches a self-organized state, raising several new questions. Key issues: • Under these strongly coupled conditions, what is the plasma configuration that emerges from these self-consistent internal physics processes? • In the strongly coupled burning plasma what maximum stability properties will the plasma access? • Can such strongly coupled burning plasmas be established and sustained with much less external power and current drive than in present experiments? What is the most attractive core burning plasma regime that can be achieved? • What is the self-consistent plasma core/scrape-off layer/divertor plasma state? iteR will provide critical information on obtaining and understanding burning plasmas. iteR’s targets are to first demonstrate Q = 10 (P alpha ~ 2P input ), in plasmas sustained by an inductive transformer (non-steady-state), and later to explore noninductively sustained plasmas with Q = 5 (P alpha ~ P input ) for longer durations. demo requirements for a high-performance plasma surpass iteR’s goals, and the Us should explore a complementary d-t facility with a more focused physics program. The scrape-off layer plasma and its interaction with material surfaces can influence the core through particle transport, the effects of which can be observed on the multiple current profile redistribution time scale of these experiments. Proposed actions: • Pursue research on existing tokamaks and the asian long-pulse tokamaks to establish fully noninductive and high-performance plasma targets for high-Q, steady-state plasmas. • Us researchers, together with international colleagues, should assess potential operating plasma scenarios and upgrades on iteR, which could enhance the performance of noninductively sustained burning plasma demonstrations. • in parallel, examine design options for construction of a Us facility, to supplement the iteR mission, focused on high P alpha /P input , high pressure, high density, high self-driven current fraction, d-t burning plasmas for durations of several current profile redistribution times. This design study should explore whether the flexible facility needed for this Thrust can be made compatible with the missions of other fusion energy science thrusts. 293
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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
Page 244 and 245: could have an impact on the identif
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Page 248 and 249: Mitigation of disruptions in the ev
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Page 254 and 255: • control alpha heating feedback
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Page 260 and 261: • determine minimum heating power
Page 262 and 263: Research should focus on developing
Page 264 and 265: estal structure need to be coupled
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Page 268 and 269: Proposed actions: Short-term: begin
Page 270 and 271: Demonstrate active control of the p
Page 272 and 273: Demonstrate burn control and contro
Page 274 and 275: Develop the means for and demonstra
Page 276 and 277: Medium-term: Test and optimize full
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Page 280 and 281: • Recruit, train and support dedi
Page 282 and 283: With this information in hand, phys
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Page 290 and 291: Element 2 — High current conducto
Page 292 and 293: Element 7 — integration of conduc
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Page 300 and 301: The Us d-t facility, studied in 1b,
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Page 304 and 305: • design and implement innovation
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Page 310 and 311: The modeling of near-surface plasma
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Page 314 and 315: • build large-size test stands wh
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Page 322 and 323: introduction Thrust 11 addresses th
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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
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• Use a combination of existing a
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chemical interactions between the s
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dose fusion-relevant environment wi
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Use a combination of existing and n
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350
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evaluate, through advanced design a
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at the time when the demo design is
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3. Computational analysis managemen
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Materials and Components: Fuel Cycl
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• employ energetic particle beams
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• develop and validate theoretica
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• develop new diagnostics for int
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• increase sustained noninductive
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368
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Proposed actions: 1. conduct two qu
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The key areas in which new knowledg
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• exploration of high-temperature
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• availability of high-power radi
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378
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• study FRc stability at small io
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techniques for integrated data anal
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4. based on the outcome of actions
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2. With information from action 1,
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388
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aCROnyMS anD abbREViatiOnS (continu
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aPPENdix c: tHEME WoRKSHoPS tHEME W
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14. d.l. humphreys, Active Realtime
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tHEME 2: CREating PREDiCtabLE HigH-
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43. t.W. Petrie, White Paper: Some
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tHEME 3: taMing tHE PLaSMa MatERiaL
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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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