CERC plasmas in the International Stellarator/Heliotron...
15
CERC plasmas in the International Stellarator/Heliotron Database J.L. Velasco 1 thanks to A. Alonso 1 , E. Ascas´ ıbar 1 , I. Calvo 1 ,C. Deng 2 , N. Pablant 3 , S. Satake 4 , F. Warmer 5 ... and all the contributors to the ISHDB 1 Laboratorio Nacional de Fusi´on, CIEMAT 2 Madison University 3 Princeton Plasma Physics Laboratory 4 National Institute for Fusion Science 5 Max Planck IPP Greifswald 16th Coordinated Working Group Meeting, 2017, Madrid
Transcript of CERC plasmas in the International Stellarator/Heliotron...
CERC plasmas in the InternationalStellarator/Heliotron Database
J.L. Velasco1
thanks to A. Alonso1, E. Ascasıbar1, I. Calvo1,C. Deng2, N. Pablant3, S.
Satake4, F. Warmer5... and all the contributors to the ISHDB
1 Laboratorio Nacional de Fusion, CIEMAT2 Madison University
3 Princeton Plasma Physics Laboratory4 National Institute for Fusion Science
5 Max Planck IPP Greifswald
16th Coordinated Working Group Meeting, 2017, Madrid
CERC in the ISHPDB
One of the goals of CWGM isto contribute to the Interna-tional Stellarator- Heliotron Confinement (Profile) Database,ISH-C(P)DB.This database is intended to compare confinement, transportand various physical phenomena which may be commonly ob-served among several stellarator-heliotron devices.ISHPDB public data consist of the results of joint researchactivities and joint papers.
1/12
EUROfusion and the ISHDB
EUROfusion wants to promote the exploitation of scientific re-sults obtained accros various experiments within EUROfusion.
Establish and exploit several databases:
WJPET1 (JET campaigns).
WPMST1 (Medium-Size Tokamak campaigns).
Stellarator/Heliotron database
Plan is to use common infrastructure using IMAS.
Should be able to handle stellarator-specific datasets.
No much progress since last CWGM.
2/12
CERC in the ISHPDB [Yokoyama et al. 2007 NF]
Improved energy confinement; highly peaked Te.
Positive and large (Er � 1 kV/m) radial electric field.
Hollow density profiles.
ECH-heated plasmas above a power threshold.
3/12
CERC profile documentation
4/12
0-D energy balance in CERC plasmas
Pb ∼ Qb ∼ ΓbTb
For the electrons, pe ∼ pECH + prad + pei ≈ pECH .
For the ions, pi ≈ pie = −pei.Ions in the
√ν regime, Γi = Γ
√ν
i .Electrons:
in the√ν regime for electron root, Γe = Γ
√ν
e .
in the 1/ν regime for ion root, Γe = Γ1/νe .
Radial electric field:Er ∼ −T ′
e/e > 0 for electron root.Er ∼ T ′
i/Zie < 0 for ion root.
It can be shown that:
Γ1/νb ∼ (ε3/2R−1B−2)(A
1/2b Z−6b )(n0bT
7/2b )
Γ√ν
b ∼ (ε3R2B−1/2)(A−1/4b Z
3/2b )(n
3/2b T
−1/4b )
pie ∼ A−1i Zin2eT−1/2e
5/12
Energy conf. and core parameters: equations
Electron energy balance:
PECH ∼ TeΓe
For electrons in the√ν regime, Γe = Γ
√ν
e :
PECHT−3/4e n−3/2e ∼ ε3R2B−1/2
For electrons in the 1/ν regime, Γe = Γ1/νe :
PECHT−9/2e ∼ ε3/2R−1B−2
TJ-II: Te reduction with ne [Estrada 2004]
LHD: Te∼n−0.6e [Ida 2003]
LHD: P ∼T−0.5e [Ida 2004]
No isotopic effect could not be revealed in W7-AS [Hirsch 2008]
6/12
Energy confinement and core parameters: ISHDB scaling
100
1000
10000
100000
0.001 0.01 0.1
P abs
n e(0
)-3/2
Te(
0)-3
/4 [
A.U
.]
R2*(a/R)3*B-1/2 [A.U]
CERC databaseν
1/2 NC scaling 1e-06
1e-05
0.0001
0.001
0.01
0.001 0.01 0.1
P abs
Te(
0)-9
/2 [
A.U
.]
R-1*(a/R)3/2*B-2 [A.U]
CERC databaseν
-1 NC scaling
7/12
Energy confinement and core parameters: ISHDB scaling
100
1000
10000
100000
0.001 0.01 0.1
P abs
n e(0
)-3/2
Te(
0)-3
/4 [
A.U
.]
R2*(a/R)3*B-1/2 [A.U]
CERC databaseν
1/2 NC scaling
7/12
Threshold to CERC
From ion to electron root:
Γ1/νe ∼> ZΓ
√ν
i (forEr < 0)⇒ needEr > 0
PECH ∼ Γ1/νe Te
ε2R3pie ∼ Γ√ν
i Ti
we have:
n−9/5e PECH ∼ (ε159/40R13/5B−1/5)(Z9/10)
TJ-II: ne ∼ P+0.34ECH ε−1.0 [Guimaraes 2008 PFR]
i.e. approximately n−9/5e P
3/5ECH ∼ ε9/5
8/12
Threshold to CERC
From ion to electron root:
Γ1/νe ∼> ZΓ
√ν
i (forEr < 0)
PECH ∼ Γ1/νe Te
ε2R3pie ∼ Γ√ν
i Ti
we have:
n−9/5e PECH ∼ (ε159/40R13/5B−1/5)(Z9/10)
8/12
Relevance for impurity hole?
Collisionality diagram (relevant for neoclassics).
Devices:
Black triangles: TJ-II
Red circles: LHD
Blue squares: W7-AS
Green elipse: W7-X (∼OP1.1 and OP1.2)
Stars are reactor scenarios.
Sign code:
thin open: CERC
full: NC validation
thick open: high Ti / im-purity hole
High Ti and impurity hole plasmas relatively close to CERCplasmas.
9/12
LHD: std. ion root vs. imp. hole [Velasco 2016 NF, 2017 EPS].
#109696 (open circles):
Medium-ne, high NBI power.
Used for NC validation[Dinklage 2013 NF; Satake 2015 ISHW].
eEr ∼ T ′i < 0.
#113208 (closed circles):
Impurity hole plasma.[Nakata, this CWGM; Velasco 2016 NF].
Er < 0 but e|Er| � T ′i .
Close to impurity screening:
Need additional effects (e.g. Φ1)
Low collisionality is key element:factor ∼ 20 in core ν∗b .
With slightly higher Te & Ti, jumpto electron root [Nagaoka 2015 NF].
2
4
6
0 0.2 0.4 0.6 0.8 1
n e [
1019
m-3
], T
e,T
i [ke
V]
r/a
neTeTi
-12
-8
-4
0
0 0.2 0.4 0.6 0.8 1
Er,
Ti’/
e, T
ine’
/nee
[kV
/m]
r/a
Ti’/eTine’/nee
Er
10/12
High Ti/impurity hole as plasmas close to trans. to CERC.
ZEr vs. T ′iScan in low collisionalities.
Connection to W7-X: threshold plasmas willbe studied in OP1.2.
Similar proposals being discussed for OP1.2impurity program.XICS key diagnostics.
11/12
Summary
New devices and new plasma conditions:
CERC database can probably expanded.
Several complementary approaches.
Impurity hole plasmas not so far from CERC in the parameterspace:
Opportunity for impurity studies in both LHD and W7-X.
Resources in EUROfusion for upgrading the database:
Requests from users?
12/12
