Advanced Tokamaks FIRE to ARIES

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Advanced Tokamaks FIRE to ARIES
"Prospects for Fusion Energy" AST 558 Dale
Meade February 21, 2005
http//fire.pppl.gov/ast558_2005.html
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Elements and Issues for a Fusion Power Plant
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Requirements for the Development of Fusion Power
General issues understood very early
Reactor plasma conditions (ntE 3x1020m-3s, Ti
20 keV, Q 25) - confinement (turbulence),
plasma heating Neutron Wall Loading 4 MWm-2
(for economic attractiveness) - material damage
40 dpa/yr with low radioactive waste - tritium
breeding (TBR gt 1) to complete the fuel cycle
Fusion Power Densities ( 5 MWm-3, gt p 10
atm) b lt? p ?/ Bc2, MHD stability and coil
engineering Plasma Wall Interaction - 2
MW m-2 thermal load on wall low impurity
levels, low tritium retention (lt 0.5
kG-T) alpha ash removal High-duty cycle,
essentially steady-state
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Modern Perspective on Fusion Electric Power
Plants

• Advanced Reactor Innovation Evaluation Studies
  (ARIES)
• carried out 10 studies
• over 15 years
• Farrokh Najmabadi
• University of California,
• San Diego, La Jolla, CA
• ARIES Web Site http//aries.ucsd.edu/ARIES/

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Directions for Improvement

• Improvement saturates at 5 MW/m2 peak wall
  loading (for a 1GWe plant).
• A steady-state, first stability device with Nb3Sn
  technology has a power density about 1/3 of this
  goal.

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A dramatic change occurred in 1990
Introduction of the Advanced Tokamak

• Our vision of a fusion system in 1980s was a
  large pulsed device.
• Non-inductive current drive is inefficient.
• Some important achievements in 1980s
• Experimental demonstration of bootstrap current
  (TFTR)
• Development of ideal MHD codes that agreed with
  experimental results.
• Development of steady-state power plant concepts
  (ARIES-I and SSTR) based on the trade-off of
  bootstrap current fraction and plasma b
  (Kessel, Jardin)

• ARIES-I was still too large and too expensive
  Utilize advance technologies
• Utilized high field magnets to improve the power
  density
• Introduced SiC composite to achieve excellent
  safety environmental characteristics.

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What is an Advanced Tokamak?
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Reverse Shear Plasmas Lead to Attractive Tokamak
Power Plants
First Stability Regime

• Does Not need wall stabilization (Resistive-wall
  modes)
• Limited bootstrap current fraction (lt 65),
  limited bN 3.2 and b2,
• ARIES-I Optimizes at high A and low I and high
  magnetic field.

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Evolution of ARIES Designs
1st Stability, Nb3Sn Tech.
ARIES-I
Major radius (m) 8.0
b (bN) 2 (2.9)
Peak field (T) 16
Avg. Wall Load (MW/m2) 1.5
Current-driver power (MW) 237
Recirculating Power Fraction 0.29
Thermal efficiency 0.46
Cost of Electricity (c/kWh) 10
Reverse Shear Option
High-Field Option
ARIES-I
6.75
2 (3.0)
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2.5
202
0.28
0.49
8.2

ARIES-RS
5.5
5 (4.8)
16
4
81
0.17
0.46
7.5

ARIES-AT
5.2
9.2 (5.4)
11.5
3.3
36
0.14
0.59
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ARIES Studies (1988-2003) have Defined the Plasma
Requirements for an Attractive Fusion Power Plant
Plasma Exhaust Pheat/Rx 100MW/m Helium
Pumping Tritium Retention
High Gain Q 25 - 50 ntET 6x1021
m-3skeV Pa/Pheat fa 90 Low rotation
Plasma Control Fueling Current Drive RWM
Stabilization
High Power Density Pf/V 6 MWm-3 10 atm Gn 4
MWm-2
Steady-State 90 Bootstrap
Lets design the smallest (cheapest) experiment to
test the critical burning plasma physics
issues.
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Advanced Toroidal Physics (100 Non-inductively
Driven AT-Mode) Q 5 as target, higher Q not
precluded fbs Ibs/Ip 80 as target,
ARIES-RS/AT90 bN 4.0, n 1 wall stabilized,
RWM feedback
Quasi-Stationary Burn Duration (use plasma time
scales) Pressure profile evolution and burn
control gt 20 - 40 tE Alpha ash
accumulation/pumping gt 4 - 10 tHe Plasma current
profile evolution 2 to 5 tskin Divertor
pumping and heat removal gt 10 - 20 tdivertor
First wall heat removal gt 1 tfirst-wall
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Fusion Ignition Research Experiment (FIRE)

• R 2.14 m, a 0.595 m
• B 10 T, ( 6.5 T, AT)
• Ip 7.7 MA, ( 5 MA, AT)
• PICRF 20 MW
• PLHCD 30 MW (Upgrade)
• Pfusion 150 MW
• Q 10, (5 - 10, AT)
• Burn time 20s (2 tCR - Hmode)
• 40s (lt 5 tCR - AT)
• Tokamak Cost 350M (FY02)
• Total Project Cost 1.2B (FY02)

1,400 tonne LN cooled coils
Mission to attain, explore, understand and
optimize magnetically-confined fusion-dominated
plasmas
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FIRE is Based on ARIES-RS Vision

• 40 scale model of ARIES-RS plasma
• ARIES-like all metal PFCs
• Actively cooled W divertor
• Be tile FW, cooled between shots
• Close fitting conducting structure
• ARIES-level toroidal field
• LN cooled BeCu/OFHC TF
• ARIES-like current drive technology
• FWCD and LHCD (no NBI/ECCD)
• No momentum input
• Site needs comparable to previous
• DT tokamaks (TFTR/JET).
• T required/pulse TFTR 0.3g-T

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Critical Issue 1- Plasma Energy Confinement
FIRE and ITER Require Modest (2.5 to 5)
Extrapolation

• Tokamaks have established a solid basis for
  confinement scaling of the diverted H-Mode.
• BtE is the dimensionless metric for confinement
  time projection
• ntET is the dimensional metric for fusion
  - ntET
  bB2tE bB . BtE
• ARIES-RS Power Plants require BtE only slightly
  larger than FIRE due high b and B.

• STs require extrapolation of 200

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Significant Progress on Existing Tokamaks
Improves FIRE (and ITER) Design Basis since FESAC
and NRC Reviews

• Extended H-Mode and AT operating ranges
• Benefits of FIRE high triangularity, DN and
  moderate n/nG
• Extended H-Mode Performance based ITPA scaling
  with reduced b degradation, and ITPA Two Term
  (pedestal and core) scaling (Q gt 20).
• Hybrid modes (AUG, DIII-D,JET) are excellent
  match to FIRE n/nG, and projects Q gt 20.
• Slightly peaked density profiles (n(0)/ltngt
  1.25)enhance performance.
• Elms mitigated by high triangularity, disruptions
  in new ITPA physics basis will be tempered
  somewhat.

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New ITPA tE Scaling Opens Ignition Regime for FIRE
Unstable side
Stable side
Systematic scans of tE vs b on DIII-D and JET
show little degradation with b in contrast to the
ITER 98(y, 2) scaling which has tE b-0.66 A
new confinement scaling relation developed by
ITPA has reduced adverse scaling with b see eq.
10 in IAEA-CN-116/IT/P3-32. Cordey et al. A
route to ignition is now available if high bN
regime can be stabilized.
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FIRE, The Movie Simulation of a Standard
H-mode in FIRE - TSC CTM GLF23 m 1
sawtooth Model - Jardin et al other effects to
be added - Jardin et al
FIRE, the Movie
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p2 ?sv? /T2
Note total power requires a volume integral
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Critical Issue 2 - High Power Densities
Requires Significant (x10) Extrapolation in
Plasma Pressure
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Modeling FIRE Burning Advanced Tokamak
Ip 4.5 MA BT 6.5 T
H-mode edge also simulated
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Steady-State High-b Advanced Tokamak Discharge
on FIRE
Pf/V 5.5 MWm-3 Gn 2 MWm-2 B 6.5T bN
4.1 fbs 77 100 non-inductive Q 5 H98
1.7 n/nGW 0.85 Flat top Duration 48 tE
10 tHe 4 tcr
FT/P7-23
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Application to ITER is also being studied as part
of ITPA.
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The proposed RWM Coils would be in the Front
Assembly of Every 3rd Port Plug Assembly
RWM coils wrapped on end of Port Plug
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FIRE AT Mode is Limited by the First Wall and Vac
Vess
Nominal operating point Q 5 Pf 150 MW,
Pf/Vp 5.5 MWm-3 (ARIES) steady-state
4 to 5 tCR Physics basis improving (ITPA)
required confinement H factor and bN
attained transiently C-Mod LHCD experiments
will be very important First Wall is the main
limit Improve cooling revisit FW design
Opportunity for additional improvement.
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Note ITER and FIRE first wall (Be to VV)
cost/PFC area equal at 0.25M/m2
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Additional Opportunities to Optimize FIRE for the
Study of ARIES AT Physics and Plasma
Technologies
ARIES AT (bN 5.4, fbs 90)
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Steps to a Magnetic Fusion Power Plant
FIRE
ARIES-RS
ITER
ITER FIRE ARIES-RS
Fusion Gain 10(H), 5(AT) 10(H), 5(AT) 25 (AT)
Fusion Power (MW) 500 - 350 150 2170
Power Density(MWm-3) 0.6 5.6 6.2
Wall Loading Gn(MWm-2) 0.6 2 4
Pulse Duration (s) (tCR, ) 500 - 3000 2 -10, 86 - gt99.9 20 - 35 2 - 5, 86 - gt99 20,000,000 steady
Mass of Fusion Core (tonnes) 19,000 1,400 13,000
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FIRE Status
Physics Validation Review successfully passed.
March 30-31, 2004 Pre-Conceptual
Activities are completed.
September 30, 2004 Ready to begin Conceptual
Design Activities. Now FIRE
is ready to be put forward as per Fusion Energy
Sciences Advisory Committee recommendation
Informal international discussions are being held
at the technical level Time to begin
reassessment as recommended by NRC Burning Plasma
Panel
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AST 558  Graduate Seminar - "Prospects for
Fusion Energy"
February 7 A Brief History of Fusion and
Magnetic Fusion Basics -  Meade February 14
Recent JET Experiments and Science Issues -
 Strachan February 21   Advanced Tokamaks FIRE
to ARIES - Meade February 28   The ARIES Power
Plant Studies Jardin March 7          IFE
basics and NIF  -  Mark Herrmann(LLNL) Midterms
and Spring Break March 21        The FESAC
Fusion Energy Plan - Goldston March 28
       Fusion with High Power Lasers  
 Sethian(NRL) April 4           ITER Physics
and Technology-  Sauthoff April 11
         Stellarator Physics and Technology -
Zarnstorff April 18          New Mirror
Approaches for Fusion - Fisch April 25
         ST Science and Technology  Peng  
May 2           FRC Science and Technology -
Cohen