- Closed magnetic confinement

I ntroduction to Nuclear Fusion

Prof. Dr. Yong-Su Na

2

To build a sun on earth

- Open magnetic confinement

- Closed magnetic confinement

3

What is closed magnetic confinement?

- Suffering from end losses

Open Magnetic System

A. A. Harms et al, “Principles of Fusion Energy”, World Scientific (2000) J.P. Freidberg, “Ideal Magneto-Hydro-Dynamics”, lecture note

max 2 min

sin B

 B



v

loss cone

loss cone

Magnetic field

ion

5

Open Magnetic System

Dunkin donuts (2010)

Is this motion realistic?

6

Donut-shaped vacuum vessel Magnetic

field

ion

Closed Magnetic System

7

Closed Magnetic System

8

Plasma needs to be confined R ₀ = 1.8 m, a = 0.5 m in KSTAR

R ₀ a

Closed Magnetic System

Magnetic field

ion

9

Magnetic field

ion

R ₀ a

Closed Magnetic System

Plasma needs to be confined

R ₀ = 6.2 m, a = 2.0 m in ITER

10

Applying toroidal magnetic field 3.5 T in KSTAR, 5.3 T in ITER

Toroidal Field (TF) coil

Toroidal direction

Closed Magnetic System

Magnetic field

ion

11

Closed Magnetic System

Applying toroidal magnetic field 3.5 T in KSTAR, 5.3 T in ITER

Toroidal Field (TF) coil

Toroidal direction

12

Toroidal Field (TF) coil

Toroidal direction

Closed Magnetic System

Magnetic field

ion

Magnetic field of earth?

0.5 Gauss = 0.00005 T

http://www.crystalinks.com/earthsmagneticfield.html

13

Magnetic field

ion

Closed Magnetic System

http://www.transformacionconciencia.com/archives/2384

Magnetic field of earth?

0.5 Gauss = 0.00005 T

14

Magnetic field

ion

Closed Magnetic System

Lesch, Astrophysics, IPP Summer School (2008)

15

What kind of drift motions?

Magnetic field

ion

Closed Magnetic System

ion

electron

16

 B

R

R R

B 1

) ( 

http://magnetoglide.wordpress.com/

Where does the gradient come from?

Closed Magnetic System

17

R R NI

B

NI d

c c













) 2

( ⁰

0 0













 ^{B l}

J B

Closed Magnetic System

 B

R R

B 1

) ( 

Where does the gradient come from?

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/toroid.html

18

2 2

, 2

2

2 1

B B qB

mv

B r B

v _L

B D



 



 









B v B

2 0 0

2 0

2

||

, qB R

mv

R D

B v  R 

Z D

v v R

B R q

m e

v 



 



 

 ^

2 )

(

1 ₂ ²

||

0 0 

Closed Magnetic System

 B

R R

B 1

) (  ion

+++

- - -

electron

19

ion +++

- - - electron

Electric field, E

Closed Magnetic System

20

0 0

, 2

) ( R R B

E

E B

D

R B

v  E   



ExB drift

ExB drift

Closed Magnetic System

ion +++

- - - electron

Electric field, E

A. A. Harms et al, “Principles of Fusion Energy”, World Scientific (2000)

21

Poloidal magnetic field required

Then, how to?

Tokamak .VS. Stellarator

Closed Magnetic System

ion +++

- - - electron

ExB drift

ExB drift Electric

field, E

22

What is a tokamak?

23

Poloidal magnetic field required

Then, how to?

Tokamak .VS. Stellarator Plasma current → Tokamak How to drive plasma current?

Closed Magnetic System

ion +++

- - - electron

ExB drift

ExB drift Electric

field, E

Will be the plasma current driven if

a toroidal magnetic field is applied?

24

Faraday‘s law

S d dt B

v d

S

 





 

Tokamak

http://www.electronics-tutorials.ws/electromagnetism/electromagnetic-induction.html

25

Tokamak

Faraday‘s law

S d dt B

v d

S

 





 

26

Plasma

Tokamak

Central Solenoid (CS)

Transformer

http://www.electronics-tutorials.ws/electromagnetism/electromagnetic-induction.html

27

Pulsed Operation!

Poloidal field

Tokamak

Plasma

Central Solenoid (CS)

http://www.electronics-tutorials.ws/electromagnetism/electromagnetic-induction.html

Plasma Current

CS Coil Current (kA)

(MA)

t (s)

t (s)

Coil Limit (stress, heating)

Inherent drawback of Tokamak!

Faraday‘s law

S d dt B

v d

S

 





 

Pulsed Operation

30

Plasma Current

CS Coil Current (kA)

(MA)

t (s)

t (s)

30

Steady-state operation

by self-generated and externally driven current d /dt ~ 0

Steady-State Operation

30

Adding vertical (equilibrium) field coils (PF: Poloidal Field)

Tokamak

31

Tokamak

Adding vertical (equilibrium)

field coils (PF: Poloidal Field)

32

Force balance by vertical field coils:

Plasma positioning

Plasma expansion force

Tokamak

J.P. Freidberg, “Ideal Magneto-Hydro-Dynamics”, lecture note v

p

B

I  



33

X

●

●

X

X X

X

Force PF coils

coil coil

current current

Force

Plasma shaping by PF coils

Tokamak

34

The plasma shape can be modified by PF coil currents.

Tokamak

35

Tokamak

Plasma positioning & shaping by PF coils

Tokamak

Adding vertical (equilibrium) field coils (PF: Poloidal Field)









J J

B B





37

Invented by Igor Tamm and Andrei Sakharov in 1952

Tokamak

Toroidalnaja kamera magnitnaja katushka

(Toroidal chamber magnetic coil)

38

Cutaway of the Toroidal Chamber in Artsimovitch's Paper Research on Controlled Nuclear Fusion in the USSR

Tokamak

Toroidalnaja kamera magnitnaja katushka

(Toroidal chamber magnetic coil)

39

T1: The world’s first tokamak, Kurchatov Institute, Moscow Russia

1958 IAEA FEC, Geneva, Switzerland

http://www.iter.org/newsline/55/1194

40

JET (Joint European Torus): R ₀ = 3 m, a = 0.9 m, 1983-today

Tokamak

http://imgarcade.com/1/spherical-tokamak/

41

JET (Joint European Torus): R ₀ = 3 m, a = 0.9 m, 1983-today

Tokamak

42

JET (Joint European Torus): R ₀ = 3 m, a = 0.9 m, 1983-today

Tokamak

43

Tokamak

http://cafe.naver.com/gamebox26.cafe?iframe_url=/ArticleRead.nhn%3Farticleid=16140

KSTAR (Korea Superconducting Tokamak Advanced Research):

R ₀ = 1.8 m, a = 0.5 m, 2007-today

44

Tokamak

45

1

campaign (2008) 2

campaign (2009) 3

campaign (2010)

Tokamak

KSTAR (Korea Superconducting Tokamak Advanced Research):

R ₀ = 1.8 m, a = 0.5 m, 2007-today

46

Tokamak

KSTAR (Korea Superconducting Tokamak Advanced Research):

R ₀ = 1.8 m, a = 0.5 m, 2007-today

47

Tokamak

KSTAR (Korea Superconducting Tokamak Advanced Research):

R ₀ = 1.8 m, a = 0.5 m, 2007-today

48

KSTAR 1 ^st plasma

Tokamak

KSTAR (Korea Superconducting Tokamak Advanced Research):

R ₀ = 1.8 m, a = 0.5 m, 2007-today

Analyse the KSTAR 1 ^st plasma

49

Tokamak









J J

B B



