Post on 26-Dec-2015
Study of negative ion surface production in caesium-free H2 plasma
PhD student:• Kostiantyn Achkasov
Tutors:• Gilles Cartry and Alain Simonin
3rd FUSENET PhD Eventin Fusion Science and Engineering
University of York, 23rd - 26th of July 2013
2
Fundamentals
3rd FUSENET PhD Event in York: 26th of June 2013
Controlled thermonuclear fusion is one of the most promising future energy sources
3
Fundamentals
Controlled thermonuclear fusion is one of the most promising future energy sources
3rd FUSENET PhD Event in York: 26th of June 2013
4
Fundamentals
ITER is the world's largest experimental tokamak nuclear fusion reactor being built at the south of France
Controlled thermonuclear fusion is one of the most promising future energy sources
3rd FUSENET PhD Event in York: 26th of June 2013
5
Fundamentals
ITER is the world's largest experimental tokamak nuclear fusion reactor being built at the south of France
Required electron temperature: 10 – 20 keV (~108 °C)
only 1 keV can be achieved with Ohmic heating
Controlled thermonuclear fusion is one of the most promising future energy sources
3rd FUSENET PhD Event in York: 26th of June 2013
6
Fundamentals
ITER is the world's largest experimental tokamak nuclear fusion reactor being built at the south of France
Required electron temperature: 10 – 20 keV (~108 °C)
only 1 keV can be achieved with Ohmic heating
Controlled thermonuclear fusion is one of the most promising future energy sources
one needs additional heating methods!3rd FUSENET PhD Event in York: 26th of June 2013
7
NBI for ITERNBI - neutral beam injection
3rd FUSENET PhD Event in York: 26th of June 2013
5.3 m
4.7 m
15 m
8
NBI for ITER
17 MW &1 MeV of neutrals
Total weight > 900 tons
Calorimeter
Bushing
RID Neutralizer Ion source and accelerator
NBI - neutral beam injection
3rd FUSENET PhD Event in York: 26th of June 2013
9
Why to use i- ?
neutrals of 1 MeV are needed to heat the ITER plasma core and ignite the fusion reactions
3rd FUSENET PhD Event in York: 26th of June 2013
10
neutrals of 1 MeV are needed to heat the ITER plasma core and ignite the fusion reactions
At such an energy:D+ → 0%D- → 56% of neutralisation efficiency
Ion neutralization
Why to use i- ?
0
10
20
30
40
50
60
70
80
90
100
0 200 400 600 800 1000
Energy of D+ or D- (keV)
Fra
ctio
n (
%)
D-
D+
3rd FUSENET PhD Event in York: 26th of June 2013
11
Ion neutralization
Necessary D- current: ~ 50 A (250 A∙m-2)
Why to use i- ?
0
10
20
30
40
50
60
70
80
90
100
0 200 400 600 800 1000
Energy of D+ or D- (keV)
Fra
ctio
n (
%)
D-
D+
neutrals of 1 MeV are needed to heat the ITER plasma core and ignite the fusion reactions
At such an energy:D+ → 0%D- → 56% of neutralisation efficiency
3rd FUSENET PhD Event in York: 26th of June 2013
0
10
20
30
40
50
60
70
80
90
100
0 200 400 600 800 1000
Energy of D+ or D- (keV)
Fra
ctio
n (
%)
D-
D+
12
new large i- source has to be developed!
Ion neutralization
Necessary D- current: ~ 50 A (250 A∙m-2)
Why to use i- ?
neutrals of 1 MeV are needed to heat the ITER plasma core and ignite the fusion reactions
At such an energy:D+ → 0%D- → 56% of neutralisation efficiency
3rd FUSENET PhD Event in York: 26th of June 2013
Present i– source
13
i- source conceptRF Driver
3rd FUSENET PhD Event in York: 26th of June 2013
• i- surface production with Cs deposition
• has many drawbacks like diffusion of Cs inside the accelerator
• is presently the only way to meet ITER requirements
14
RF Driver
Present i– sourcei- source concept
3rd FUSENET PhD Event in York: 26th of June 2013
Alternative solutions to the use of Cswould be highly valuable for the future fusion i- sources!
15
Present i– source
RF Driver• i- surface production with Cs deposition
• has many drawbacks like diffusion of Cs inside the accelerator
• is presently the only way to meet ITER requirements
i- source concept
3rd FUSENET PhD Event in York: 26th of June 2013
16
Helicon reactor PHISIS
• H2 and D2 plasma
• P = 20 – 900 W• no magnetic field• preactor = 0.2 – 2 Pa
• capacitively coupled plasma mode
Experimental set-up
Graphite samplePump
Pyrex tube
Antenna
Coils
Mass Spectrometer Hiden EQP 300
3rd FUSENET PhD Event in York: 26th of June 2013
17
Experimental set-up
Helicon reactor PHISIS
• H2 and D2 plasma
• P = 20 – 900 W• no magnetic field• preactor = 0.2 – 2 Pa
• capacitively coupled plasma mode
3rd FUSENET PhD Event in York: 26th of June 2013
18
Langmuir probe
Sample
Experimental set-up
Mass Spectrometer
3rd FUSENET PhD Event in York: 26th of June 2013
19
Measurement principle
VMS Vs Vp
Mass Spectrometer Plasma Sample
E
0
3rd FUSENET PhD Event in York: 26th of June 2013
VMS Vs Vp
Mass Spectrometer Plasma Sample
20
E
0 10 20 30 40 50 60 70 80
0.01
0.1
1 0.2 Pa H2,100 W,V
p=21V
Vs=-130V D=37mm,
H2
+90%, HOPG, WS
H- c
ou
nts
/s
Energy (eV)
0
Negative ion distribution function (NIDF)
Measurement principle
3rd FUSENET PhD Event in York: 26th of June 2013
0 10 20 300.01
0.1
1
Energy (eV)
no
rma
lis
ed
in
ten
sit
y (
arb
.u)
Fmeasured
(E)1 Pa H2,60 W, V
p=7V,V
s=-95V
21
Modeling of the NIDF
3rd FUSENET PhD Event in York: 26th of June 2013
0 10 20 300.01
0.1
1
Energy (eV)
no
rma
lis
ed
in
ten
sit
y (
arb
.u)
Fmeasured
(E)
f(E) SRIM1 Pa H
2,60 W, V
p=7V,V
s=-95V
22
Modeling of the NIDF
SRIM: the stopping and range of ions in matter
3rd FUSENET PhD Event in York: 26th of June 2013
0 10 20 300.01
0.1
1
Energy (eV)
no
rma
lis
ed
in
ten
sit
y (
arb
.u)
Fmeasured
(E)
f(E) SRIM1 Pa H
2,60 W, V
p=7V,V
s=-95V
23
Modeling of the NIDF
×× Plasma transmissionNIDF of i- emitted by
the surface
Surface
Mass spectrometer transmission
3rd FUSENET PhD Event in York: 26th of June 2013
0 10 20 300.01
0.1
1
Energy (eV)
no
rma
lis
ed
in
ten
sit
y (
arb
.u)
Fmeasured
(E)
f(E) SRIM1 Pa H
2,60 W, V
p=7V,V
s=-95V
24
Modeling of the NIDF
SRIM
×× Plasma transmissionNIDF of i- emitted by
the surface
Surface
Mass spectrometer transmission
3rd FUSENET PhD Event in York: 26th of June 2013
0 10 20 300.01
0.1
1
Energy (eV)
no
rma
lis
ed
in
ten
sit
y (
arb
.u)
Fmeasured
(E)
f(E) SRIM1 Pa H
2,60 W, V
p=7V,V
s=-95V
25
Modeling of the NIDF
SRIM SIMION
×× Plasma transmissionNIDF of i- emitted by
the surface
Surface
Mass spectrometer transmission
3rd FUSENET PhD Event in York: 26th of June 2013
0 10 20 300.01
0.1
1
Energy (eV)
no
rma
lis
ed
in
ten
sit
y (
arb
.u)
Fmeasured
(E)
f(E) SRIM f ''(E) modeling
1 Pa H2,60 W, V
p=7V,V
s=-95V
26
• good agreement between F’’(E) and Fmeasured(E)
Modeling of the NIDF
3rd FUSENET PhD Event in York: 26th of June 2013
0 10 20 300.01
0.1
1
Energy (eV)
no
rma
lis
ed
in
ten
sit
y (
arb
.u)
Fmeasured
(E)
f(E) SRIM f ''(E) modeling
1 Pa H2,60 W, V
p=7V,V
s=-95V
27
• good agreement between F’’(E) and Fmeasured(E)
• SRIM calculation: C-H layer with 30% of hydrogen on the surface
Modeling of the NIDF
3rd FUSENET PhD Event in York: 26th of June 2013
NIDF studyof different carbon materials
28
highly oriented pyrolitic graphite (HOPG)
-40 -20 0 20 40 60 80
10
100
1000
10000
100000
35 °C 200 °C 400 °C 782 °C
Vs= - 130 V
= 0°
Inte
nsity
(ar
b. u
nits
)
Energy (eV)
HOPG 50 eV
3rd FUSENET PhD Event in York: 26th of June 2013
29
-10 0 10 20 30 40 50 60 70
0.01
0.1
1
35 °C
Vs= - 130 V
= 0°
Inte
nsity
(ar
b. u
nits
)
Energy (eV)
HOPG 50 eV
NIDF studyof different carbon materials
highly oriented pyrolitic graphite (HOPG)
3rd FUSENET PhD Event in York: 26th of June 2013
30
-10 0 10 20 30 40 50 60 70
0.01
0.1
1
35 °C
Vs= - 130 V
= 0°
Inte
nsity
(ar
b. u
nits
)
Energy (eV)
HOPG 50 eV
F”(E,θ)30% H
NIDF studyof different carbon materials
highly oriented pyrolitic graphite (HOPG)
3rd FUSENET PhD Event in York: 26th of June 2013
31
0
0.01
0.1
1
35 °C 200 °C
Vs= - 130 V
= 0°
Inte
nsity
(ar
b. u
nits
)
Energy (eV)
HOPG 50 eV
F”(E,θ)30% H
NIDF studyof different carbon materials
highly oriented pyrolitic graphite (HOPG)
3rd FUSENET PhD Event in York: 26th of June 2013
32
0
0.01
0.1
1
35 °C 200 °C
Vs= - 130 V
= 0°
Inte
nsity
(ar
b. u
nits
)
Energy (eV)
HOPG 50 eV
F”(E,θ)20% H
F”(E,θ)30% H
NIDF studyof different carbon materials
highly oriented pyrolitic graphite (HOPG)
3rd FUSENET PhD Event in York: 26th of June 2013
33
H coverageon HOPG decreases with temperature
0
0.01
0.1
1
35 °C 200 °C
Vs= - 130 V
= 0°
Inte
nsity
(ar
b. u
nits
)
Energy (eV)
HOPG 50 eV
F”(E,θ)20% H
F”(E,θ)30% H
NIDF studyof different carbon materials
highly oriented pyrolitic graphite (HOPG)
3rd FUSENET PhD Event in York: 26th of June 2013
34
yield comparison
0 100 200 300 400 500 600 700 800
10000
100000
1000000
Vs= - 130 V
= 0°
HOPG
Tot
al y
ield
(ar
b. u
nits
)
T,°C
NIDF studyof different carbon materials
3rd FUSENET PhD Event in York: 26th of June 2013
35
yield comparison
0 100 200 300 400 500 600 700 800
10000
100000
1000000
Vs= - 130 V
= 0°
HOPG
Tot
al y
ield
(ar
b. u
nits
)
T,°C
NIDF studyof different carbon materials
-10 0 10 20 30 40 50
HOPG
H- c
ount
s/s
(arb
uni
ts)
Energy (eV)
3rd FUSENET PhD Event in York: 26th of June 2013
36
yield comparison
0 100 200 300 400 500 600 700 800
10000
100000
1000000
Vs= - 130 V
= 0°
HOPG
Tot
al y
ield
(ar
b. u
nits
)
T,°C
NIDF studyof different carbon materials
% H
3rd FUSENET PhD Event in York: 26th of June 2013
37
yield comparison
0 100 200 300 400 500 600 700 800
10000
100000
1000000
Vs= - 130 V
= 0°
HOPG BDD
Tot
al y
ield
(ar
b. u
nits
)
T,°C
NIDF studyof different carbon materials
% H % H
% H
Boron-doped diamond:
BDD
3rd FUSENET PhD Event in York: 26th of June 2013
38
yield comparison
0 100 200 300 400 500 600 700 800
10000
100000
1000000
Vs= - 130 V
= 0°
HOPG BDD ID
Tot
al y
ield
(ar
b. u
nits
)
T,°C
NIDF studyof different carbon materials
% H
biasing problemsbelow 400°C
% H % H
% H
Intrinsic diamond: ID
3rd FUSENET PhD Event in York: 26th of June 2013
0 100 200 300 400 500 600 700 800
10000
100000
1000000
Vs= - 130 V
= 0°
HOPG BDD ID
Tot
al y
ield
(ar
b. u
nits
)
T,°C
39
yield comparison
% H % H
% H
% H
Raman spectroscopy:
sp3/sp2 BDD
sp3/sp2 HOPG
biasing problemsbelow 400°C
NIDF studyof different carbon materials
3rd FUSENET PhD Event in York: 26th of June 2013
40
sp3/sp2 phase ratio
J. Robertson, Materials Science and Engineering, R37 (2002)
Raman spectroscopy:
sp3/sp2 BDD
sp3/sp2 HOPG
NIDF studyof different carbon materials
3rd FUSENET PhD Event in York: 26th of June 2013
HOPG gives the highest i- yield at Troom
ID gives the highest i- yield at elevated T: 500°C
Conclusions
413rd FUSENET PhD Event in York: 26th of June 2013
HOPG gives the highest i- yield at Troom
ID gives the highest i- yield at elevated T: 500°C
proper use of MS diagnostic and modeling allows to determine H coverage on the sample surface
Conclusions
423rd FUSENET PhD Event in York: 26th of June 2013
HOPG gives the highest i- yield at Troom
ID gives the highest i- yield at elevated T: 500°C
proper use of MS diagnostic and modeling allows to determine H coverage on the sample surface
MS combined with Raman spectroscopy shows:
the phase ratio sp3/sp2 changes when increasing T which alters the H surface coverage and the i- yield
Conclusions
433rd FUSENET PhD Event in York: 26th of June 2013
HOPG gives the highest i- yield at Troom
ID gives the highest i- yield at elevated T: 500°C
proper use of MS diagnostic and modeling allows to determine H coverage on the sample surface
MS combined with Raman spectroscopy shows:
the phase ratio sp3/sp2 changes when increasing T which alters the H surface coverage and the i- yield
New materials with the optimal sp3/sp2 state have to be probed deeper understanding is crucial
Conclusions
443rd FUSENET PhD Event in York: 26th of June 2013
Perspectives
453rd FUSENET PhD Event in York: 26th of June 2013
Next steps
prove experimentally the H surface coverage change with T:• Infrared Spectroscopy• Temperature Programmed Desorption Spectroscopy
Perspectives
463rd FUSENET PhD Event in York: 26th of June 2013
Next steps
prove experimentally the H surface coverage change with T:• Infrared Spectroscopy• Temperature Programmed Desorption Spectroscopy
try out new materials:• low work-function materials (Gd, Ba, ...)• large band-gap insulators (Si, GaAs,…)
Perspectives
47
Next steps
prove experimentally the H surface coverage change with T:• Infrared Spectroscopy• Temperature Programmed Desorption Spectroscopy
try out new materials:• low work-function materials (Gd, Ba, ...)• large band-gap insulators (Si, GaAs,…)
3rd FUSENET PhD Event in York: 26th of June 2013
Final steps
Test the chosen material in a real negative ion source (Cybele) equipped with an extraction device and a particle accelerator (MANTIS) in CEA-Cadarache
The End
Thank you for your attention
and time!
483rd FUSENET PhD Event in York: 26th of June 2013