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Fusion (?) Energy (??) Science (???) and
its Gaps and Integration *
Leonid E. Zakharov (PPPL)
DOE Workshop on Integrated Simulations for Magnetic Fusion Energy SciencesMay 18, 2015
∗This work is supported by US DoE contract No. DE-AC02-09-CH11466
PRINCETON PLASMAPHYSICS LABORATORY
PPPL
Abstract 2/17
It would be very good if the issue would be in “gaps” and “integration”, which require the existence of
components and a vision of integration objectives. Unfortunately, FES has neither components in critical
area, (such as confinement, plasma edge, stability, power extraction, fueling) nor realistic vision of the
burning plasma and its demonstration.
In contrast, an alternative approach to fusion, called LiWall Fusion (LiWF) was formulated, which sug-
gested the “best possible” solutions to the mentioned problem and to the burning plasma (either in a the
JET-type facility with demonstration of QDT = 5 or in a DEMO facility, PDT ≃ 100 MW, R/a/b =4/1/1.6, Ipl ≃ 5 MA, Btor ≃ 6 T).
The LiWF is self-consistent and integrated at the basic level. Its research “gaps” are evident and further
“integration” is straightforward.
The LiWF approach to fusion needs a practical implementation.
PPPPRINCETONPLASMA PHYSICSLABORATORY
PPPPRINCETONPLASMA PHYSICSLABORATORY
THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
Contents 3/17
1 Confinement: the mess and the science 4
1.1 The notion of the best possible confinement . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Confinement is a technology issue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Confinement and power extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Plasma edge and the confinement zone 8
2.1 LiWF understanding of the plasma edge . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 RMP on DIII-D have determined the edge position . . . . . . . . . . . . . . . . . . . . 10
2.3 ETB industry of cooking FE“Science” . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3 Stability 13
4 Energy. What is the fusion DEMO ? 14
4.1 DEMO: mission, parameters and burning plasma . . . . . . . . . . . . . . . . . . . . 15
4.2 LiWF vs FES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5 Fusion. Summary 17
PPPPRINCETONPLASMA PHYSICSLABORATORY
PPPPRINCETONPLASMA PHYSICSLABORATORY
THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
1 Confinement: the mess and the science 4/17
Porous metal brick
Tc T(x) Tedge
Cold wall
Hot gasTgas
x
gas termal conduction
c
TgasT(x)
edge
c edge cold gas
Tedge
recycling
density n(x) Zi
D D+
Recycling
turbulent1 keVPlasma
80 keV
thermo−conduction 5Stronger Btorup to the limits on the costwith "salt−water" numerical
models of plasma dynamics
Higher heat
ing
dumpedto
and
dive
rtor
to
plat
es
Larger Iplasma
with no
way to
preventdisruptions
Big
ger
size
Exa scale HPC
with
no
unde
rsta
ndin
gof
turb
ulen
t los
ses
Pow
erel
ectr
ons
anom
alou
s
and the stuctural strength
Fusion of 5 “Bigs”
Tgas
T(x)Hot gas
Tedge
edge
x
gas
x
gas body,
c edge
only diffusion
Pumping wall
c
density n(x)
T(x)
flowfree gas
T(x), 50% Recycl
Pumping walls prevent edge cooling
Li PFC
Plasma16 keV
80 keV NBI
and particle lossesdiffusive energy
D+
LiWF
(Lithium Wall Fusion)
1 g/s - Li flow rate
for pumping 1022/s
200o C< TLiLi <400o
high metal χe high χe in toroidal plasmas
modest gas χg modest ion χi
modest diffusion Dg modest plasma diffusion Di
“fueling” by gas injection NBI fueling of the plasma core
heating by gas injection NBI heating of the plasma core
PPPPRINCETONPLASMA PHYSICSLABORATORY
PPPPRINCETONPLASMA PHYSICSLABORATORY
THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
1.1 The notion of the best possible confinement 5/17
The pumping Li introduces
the best possible confinement regime,
which is determined
by plasma diffusion
Its Reference Transport Model (RTM) for the core is simple and reliable Γi,e = χneo−classicsi ∇n
Z0 PlVac
R0 0 .2 .4 .6 .8
-.4
-.2
0
.2
.4
I=.02867
PSI_03
PSI_04
PSI_05
PSI_07
PSI_08
PSI_09
PSI_12
PSI_13
Flux loopMagnetic probe
RTM easily reproduced global CDX-U param-eters (2007)
Parameter CDX-U RTM RTM-0.8 glf23 Comment
N , 1021part/sec 1-2 .98 0.5 0.8-3 Gas puff rate
βj 0.160 0.151 0.150 0.145 measured βj
li 0.66 0.769 0.702 0.877 internal induc
V, Volt 0.5-0.6 0.77 0.53 0.85 Loop Voltage
τE, msec 3.5-4.5 2.7 3.8 2.3
ne(0), 1019part/m3 0.9 0.7 0.9
Te(0), keV 0.308 0.366 0.329
Ti(0), keV 0.031 0.029 0.028
All MHD activity disappeared with Li surface.
Only with after appropriate calibration it was possible to extract the energy confinement time in CDX-U
(pulse length 20 msec)
PPPPRINCETONPLASMA PHYSICSLABORATORY
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THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
1.2 Confinement is a technology issue 6/17
Plasma pumping liquid lithium layer is the key to new regimes.
Distributor box
Gui
de p
late
Lithiu
m flo
w
Heat s
ink
Exhaust tubeCollector:
Driving wire
Fee
ding
tube
Interface cylinderWire enclosure
Distributor:
Guide plate
Heat sink
Exhaust tube
Collector:
Screw
Driving wire
Feedingtube
LidFilter layerSide flange
Side flangeBox
Open top filterBox
Interface cylinder
Wire enclosureto Drain
DistributorHeat sink
Plasma cross−section
The criti-
cal technological invention of 247 FLiLi was made in 2011-2012, first field tests were per-
formed on HT-7 (2012), EAST (2014) in ASIPP (Hefei,China)
Gravity driven viscous flow, No interaction with ~B
0.1 mm thick LiLi layer
≃ 1 cm/s velocity
≃ 1 g/s flow rate
200oC<TLiLi <400oC
The of 247 FLiLi technology,
rather than “core turbulent transport” (missing the major effect on confinement),
needs its “integration” to mentality of the community and practical implementation.
PPPPRINCETONPLASMA PHYSICSLABORATORY
PPPPRINCETONPLASMA PHYSICSLABORATORY
THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
1.3 Confinement and power extraction 7/17
PFC in the divertor cannot reliably work at heat flux qheat > 10 MW/m2. There is nosolution to the problem based solely on improvements in materials.
Suggested by LiWF,
a significantly enhanced confinement and reduction in heating power
is a practical approach
to the resolution of the power extraction problem.
PPPPRINCETONPLASMA PHYSICSLABORATORY
PPPPRINCETONPLASMA PHYSICSLABORATORY
THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
2 Plasma edge and the confinement zone 8/17
In figure, the normal person see the same sudden drop of ion and electron temperatureat the plasma edge. The certified experts of TTF see a remarkable “transport” barrier
Figure 4 Kinetic profiles from a QDB (103740) and ITB with an L-mode edge (99849). (a) Ion and (b) electron temperatures, (c) electrondensity, (d) radial electric field, and (e) E x B shearing rate. The picture ofan H-mode below was taken arbitrarily from paper “The quiescent double barrier regimein DIII-D” by C. M. Greenfield, K. H. Burrell, E. J. Doyle et al. Plasma Phys. Control. Fusion44 (2002) A123-A135. There are many similar pictures from different regimes on DIII-Dand from other machines.
What GK theory sees on these plots is a sharp gradient of electrontemperature in the pedestal region, which is located inside the sepa-ratrix (ρ = 1). For GK this automatically means the presence of twozones of confinement: a core and the “edge transport barrier” (ETB)with suppressed radial transport.
At the same time, a normal physicist would notice a similar sharpgradient on the ion temperature. In this example it is clearly locatedoutside the separatrix. Nobody would suggest a transport barrier inthe open field line region where there is no confinement. The normalphysicist would reasonably suggest that the sharp electron temper-ature gradient has the same reason - open field lines, rather thanmythical “edge transport barrier”. Accordingly the pedestal regionhas no electron confinement.
DIII-D experiments with QHM and especially with RMP has confirmedthe common sense and the interpretation of the normal physicist: forelectrons the confinement zone extends from the magnetic axis to thetop of the temperature pedestal. In the pedestal region not only thereis no any transport “barrier”, there is no confinement at all.
FES advertised the shear flow stabilization of the plasma edge as a great achievement ofgyro-kinetic theory. In contrast, this is an outstanding example in a series of failures ofa misleading theory.
PPPPRINCETONPLASMA PHYSICSLABORATORY
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THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
2.1 LiWF understanding of the plasma edge 9/17
Edge plasma temperature is determined self-consistently by the particle and power
fluxes (Krasheninnikov)
Energy fluxes Qi,e are transported to the wall by the particle flux:
5
2Γedge−walle T edge
e = Qcore−edgee =
∫
V
PedV︸ ︷︷ ︸heat sourcefor electrons
−∂
∂t
∫
V
3
2nTedV,
5
2Γedge−walli T edge
i = Qcore−edgei =
∫
V
PidV︸ ︷︷ ︸heat sourcefor ions
−∂
∂t
∫
V
3
2nTidV.
(2.1)
Edge temperature does not depend on transport coefficients near the edge. Potential∇n-driven turbulence (e.g., TEM) also would have no effect on T edge.
This property of T edge allows to determine the real position of the plasma edge
and the size of the energy confinement zone
The confinement zone is not what TTF experts are thinking
and what the “first principles” codes are simulating
PPPPRINCETONPLASMA PHYSICSLABORATORY
PPPPRINCETONPLASMA PHYSICSLABORATORY
THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
2.2 RMP on DIII-D have determined the edge position 10/17
RMP experiments on DIII-D have determined the size of the confinement zone
1. The pedestal T pedestale is found insensitive to RMP
→ T pedestale is the T edge
e →
The tip of the Te pedestal is the boundary of theconfinement zone for electrons.
2. RMP do penetrate into the confinement zone:
The gradientsn′(x), T ′
e(x)
in the core are reduced by RMP - indication of“screening”.
3. Different positions of the “edge” for Te, Ti, ne arepossible
Claims about flow shear “stabilization” of turbulence and
suppressed transport in the pedestal are baseless.
It is just opposite: there is no electron confinement
in the pedestal region.
The pedestal is situated outside the confinement
zone
0 kA, 2 kA, 3 kA IRMP−coil
T.Evans at al., Nature physics 2, p.419, (2006)
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THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
2.3 ETB industry of cooking FE“Science” 11/17
The most prominent examples:
1. Shear flow stabilization of turbulence in the pedestal region (to the level below neo-classical transport);
2. Screening the external magnetic field perturbations (RMP) by plasma sheared flow;
3. Huge edge localized bootstrap current, “confirmed” by GIGO 5-D kinetic simulations;
4. “Peeling-ballooning” model of ELM stability;
5. EPED model of the width/height of the pedestal.
TTF failed with integration of the plasma edge and the core(the idea proposed by S.Krasheninnikov in 1998).
Its “flagship” codes cannot even reproduce a flat temperature of the plasma with no re-cycling (no cooling) after months of bothering the Titan supercomputer (18,000 x 78,000PGU processors).
ASTRA code does this in a fraction of second at a laptop.
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THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
Scrape Off Layer Currents 12/17
SOLCs exist even in the most quiet plasma. They are the key to the understanding of the
plasma edge.
Todd Evans, Hiro Takahashi and Eric Fredrickson (NF,2004) have found a link between
SOLCs and MHD activity on DIII-D. SOLCs are the first candidate for intrinsic perturba-
tions, which determine the width of the temperature pedestal.
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THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
3 Stability 13/17
Stability is a mess in FES: Greenwald limit, ELMs, sawteeth, neo-classical tearing modes.
In disruption simulation all numerical codes are essentially hydrodynamic modified by aLorentz force.
(a) Inertial dynamics,(b) "extended MHD" plasma core model with equations either irrelevant to MHD or questionable,() mixture of all physics length scales,(d) inappropriate substitution of the vacuum region by a fake plasma with Spitzer resistivity at the openfield lines,(e) simplistic wall geometry,(f) the "salt-water" boundary condition for the plasma flow to the wall,(g) misalignment of the laboratory numerical grid with the magnetic field,(h) Courant time step and Lundquist number limitations
all makes the existing 3-D code, in the words of W.Pauli, "not even wrong", they are uncorrectable.
At the same time, the unstoppable flow of cartoons generated by M3D, one of “flagship” MHD code of PPPL,
does not forget to attack the rigorous and experimentally validated WTKM theory of VDE disruptions.
What does FES support ? The answer: this flow of cartoons and speculations on the “halo” corrents,
The top achievement of FES integration of stability with burning plasma (ITER) is a diver-tor based on tungsten, which is the best poison for the high temperature plasma.
Instead LiWF suggests the best possible stability regime: no Greenwald limit, no ELMs,
no sawtooth, Ipl = 5 MA, Btor = 6 T for burning plasma, fully controlled by NBI and
conventional external means
PPPPRINCETONPLASMA PHYSICSLABORATORY
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THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
4 Energy. What is the fusion DEMO ? 14/17
In conventional fusion there is no valuable DEMO concept.
The 100-200 MW FFRF of the LiWF with its innovative burning plasma regime is the first
realistic model of DEMO. It has both fusion and fusion-fission missions
On the left is my recommendation
to Jiangang Li on the concept for
the next-step (two) DEMO devices
in China
Two similar devices, DEMO-D (no
tritium) and DEMO-T (with DT
power) are necessary, in order to
assure the success and resolution
of potential operational problems in
activated DEMO-T.
PPPPRINCETONPLASMA PHYSICSLABORATORY
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THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
4.1 DEMO: mission, parameters and burning plasma 15/17
LiWF suggests a realistic, science based DEMO for burning plasma
z EqRcnstr
r 0 2 4 6
-4
-2
0
2
4
I=-3.086
I=-7.9
I=-6.4
I=-6.4
I=-7.9
I=-3.086
I=4.9695
I=1.0719
I=4.9695
I=1.0719
I=-3.213
I=-3.213
I=-1.471
I=-1.471
I=0
I=0
Ip=5.000000 [MA]
TFCoil
Space for Heliumexhaust system
Space for LLD
Blanketspace
=-5.8 Vsec0Ψ Parameter FFRF
dblanket,m 1
am, Rm 1.0, 4.0
V plm3, S
plm2 130, 230
n20 0.4
ENBIkeV 120
Ti+Te
2|keV 24-27
Bt,T 4-6
Ipl,MA 5
∆Ψf−top,V sec 40
∆tinductivef−top,s >4000
Wth,MJ 42
τ indE,sec 20-7
PNBIMW 2-5
PDTMW 70-100
Active fission core power80-4000 MW. 1 10 100 1000
0
20
40
60
80
100PNBI=4 MW
Recycling=0.1Recycling=0.2
Recycling=0.33
Recycling=0.5
Recycling=0.7
PDT, MW
χe/DPresent high recycling regimes
PDT vs electron anomaly
At the practical level of Recycl < 0.5, the burning plasma regime with
PDT = 50 − 100 MW is possible in FFRF
Remarkably, a robust “hot-ion” regime was found (thanks to G.Hammett) where the cy-clotron radiation keeps Te < Ti even with the α-particle heating of electrons.
PPPPRINCETONPLASMA PHYSICSLABORATORY
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THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
4.2 LiWF vs FES 16/17
1. LiWF resolves the confinement problem: the best possible, particle diffusion based, confine-ment regime with expected by order of magnitude better confinement time then presently achieved
FES: misrepresents the confinement as core transport problem, never answered the basic question “Whythere is a core and a pedestal ?”
2. LiWF gives the understanding of the plasma edge and the temperature pedestal
FES: is trapped to the notion of the “edge transport barrier” and never understood the plasma edge
3. LIWF: the best possible stability regime (no sawteeth, ELMs, density limit disruptions), and wellpredictable plasma profiles
FES: a mess with stability when everything can be unstable. Mess in interpretations based on halo currents.Lack of MHD numerical models for macroscopic plasma dynamics
4. LIWF gives: only practical way to resolve the power extraction problem
FES: relies on a miracle with material development without touching the faulty plasma physics approach
5. LIWF suggests innovative approaches to DT fueling (120 kV NBI), tritium recycling, stationaryburning plasma, overall plasma control, etc
FES has no clue how to handle these “unresolvable” problems
6. Finally
LiWF gives a realistic possibility of 100 MW (R/a=4 m/1 m, Ipl=5 MA) DEMO tokamak facility withQelectric >1
FES has no clue what what is a magnetic fusion DEMO
LiWF is backed up by a clean, predictable plasma physics and relies on realistic
technologies
PPPPRINCETONPLASMA PHYSICSLABORATORY
PPPPRINCETONPLASMA PHYSICSLABORATORY
THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference
5 Fusion. Summary 17/17
The critical time for integration of LiWF into present program was missed: 3 interruptions
of 247 FLiLi development (funded by taxation of non-DoE projects of PPPL), installation of
a tungsten divertor on EAST (a non-sense for the 1000 s pulse target).
We already missed the critical time for developing the 247 FLiLi technology and a chance
to convince JET to make the DT experiment in LiWF regime and demonstrate QDT = 5.
In the case of failure of JET with obtaining QDT = 1, not compensated by a tangibleother success in fusion, the negative effect on the worldwide fusion program could bewell predicted.
16 years long DoE ignorance of LiWF has to be terminated. LiWF is not LDRD.
LiWF is the only realistic way to burning plasma goal.
A dedicated DoE project should be initiated on 247 FLiLitechnology.
The integration of LiWF and removing gaps is straightforward.
PPPPRINCETONPLASMA PHYSICSLABORATORY
PPPPRINCETONPLASMA PHYSICSLABORATORY
THEORYPPPLLeonid E. Zakharov, DOE Workshop on Integrated Simulations for Magnetic Fusion Energy Sciences, May 18, 2015, Teleconference