Fusion (?) Energy (??) Science (???) and its Gaps and ... · Abstract 2/17 It would be very good if the issue would be in “gaps” and “integration”, which require the existence

Google:[Leonid Zakharov] →http://w3.pppl.gov/~zakharov

5/18/2015 10:21 /w3/Tlk/PPPL15/May18/150518-FES.Src

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


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




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




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)




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.




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.




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.




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




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)




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.




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.




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




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.




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.




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




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.




Documents

Fusion (?) Energy (??) Science (???) and its Gaps and ... · Abstract 2/17 It would be very good if the issue would be in “gaps” and “integration”, which require the existence