DT polarization and Fusion Process
Magnetic Confinement Inertial Confinement
Persistence of the Polarization - Polarized D and 3He in a Tokamak - DD Fusion induced by Laser on polarized HD
The “Few-Body” Problems
Static Polarization of HD Dynamic Polarization of HD and DT
POLAF Project at ILE (Osaka)
Conclusion
DT Polarization for ICF
DT polarization and Fusion Process
(Kulsrud, 1982)(More, 1983)D + T → 4He (3.5 Mev) + n (14.1 MeV) + 17.6 MeV
S = ½S = 1
S = 3/2S = ½
95% – 99%D + T → 5He (3/2+) → 4He + n
1% – 4%
S = 3/23/2
1/2
-1/2
-3/2
S = 1/21/2
-1/2
4 states
2 states
2/3 of the interactions contribute to the reaction rate
If D and T are polarized then - all interactions contribute
- n and α have preferential directions Sin2(θ)- n from DD fusion are suppressed QSF (Jülich – Gatchina)
50 % Increasein released energy
The question is to know if the polarization will persist in a fusion process ?Depolarization mechanisms are small:
1) Inhomogeneous static magnetic fields, 2) Binary collisions,3) Magnetic fluctuations , 4) Atomic effects
(3.37 1011 J/g)
Plasma Density n = 1014 (cm-3) ; Confinement Time τ = 10 (sec) Lawson Criterion (n τ > 1015 (sec/cm3)
Fusion by Magnetic Confinement – (ITER)
ITER
Plasma Volume = 873 m3
τ = 300 (sec)
Power = 500 MW
Fusion by Inertial Confinement – (MEGAJOULE)
Plasma Density n = 1026 (cm-3) ; Confinement Time τ = 10-10 (sec) Lawson Criterion (n τ > 1015 (sec/cm3)
ICF
Target 3mm radiusCarbone &
4 mg cryogenic DT
2000 times compressed300 g/cm3
5 keV
825 MJ within 100 ps
J. MEYER-TER-VEHN, Nucl. Phys. News, Vol 2 N° 3 (1992) 15
A:unpolarized DT
B:polarized DT
At fixed G: EB / EA < 0.7
for G=100 EA = 880 kJ EB = 510 kJ
EAmin = 450 kJ
EBmin = 290 kJ
for E = 1 MJ GA = 140
GB = 307
DDD2T2
DTD2 T2
?
Fusion by Magnetic Confinement – (ITER)
Persistence of the Polarization
- Injection of Polarized D and 3He in a Tokamak (A. Honig and A. Sandorfi)
D + 3He → 4He + p + 18.35 MeV
(DIII-D Tokamak of San Diego, USA)
Expected: 15% increase in the fusion rate
- Powerful Laser on a polarized HD target → P and D Plasma
P + D → 3He + γ + 5.5 MeV
Expected: Angular distribution of the γ ray Change in the cross section
D + D → 3He + n + 3.267 MeV
Expected: Change in the total cross section Sin2θ angular distribution of the neutrons
Powerful Laser (Terawatt)creates a local plasmaof p and d ions (5 KeV)
5.5 MeV γ ray fromp + d → 3He + γ
2.45 MeV n fromd + d → 3He + n
Tentative Set-Up
Polarized HD Target25 cm3
H (p) polarization > 60%D (d) vect. polar. > 14%
200 mJ, 160 fs 4.5 µm FWHM
970 nm, ~ 1018 W/cm2
The “Few-Body” Problem
d
1/2 1
p d
3He
γ
dσ4/dωγ ~ (1+ cos2 θ) * (S = 3/2)
σ0 (10 keV) = 18 µbarn **1 - 10 radiative captures/laser shot ?
For polarized plasma, angular dependence relative to the polarization axis, but forward peaked, small cross section and almost impossible to detect the γ (EM background).
dσ5/dωn ~ sin2 θ *** (S = 2)
σ n5 / σ0 < 0.5 ; σ0 (1.5 MeV) = 100 mbarn ***
For polarized plasma, angular dependence perpendicular to the polarization axis, large cross section and “easy” detection of the very slow neutrons. Possibility to rotate the polarization of the RCNP HD target without any other change. High “D” polarization possible by AFP.
* M. Viviani ** G. J. Schmid PR C52, R1732 (1995) *** A. Deltuva , FB Bonn (2009)
HD Plasma5 keV
3He
d d
n
POLAF proposal (RCNP, ILE and ORSAY) with themulti-detector “MANDALA” at ILE - Osaka .
An energy resolution of 28 keV for 2.45-MeV DD neutrons is achieved with MANDALA.
An energy resolution of 28 keV for 2.45-MeV DD neutrons is achieved with MANDALA.
13.42 m 13.42 m
Target Chamber
Target Chamber
MANDALAMANDALADD neutron energy [MeV]
Co
un
t ΔE
2
5.82
)()(
keV
keVE
Ti
D ~ 2.2 m
neutron detectorneutron detector
t10 cm PMT
10 cm
BC-408 scintillat
or×422 ch
An energy resolution of 28 keV for 2.45-MeV DD neutrons is achieved with MANDALA.
An energy resolution of 28 keV for 2.45-MeV DD neutrons is achieved with MANDALA.
13.42 m 13.42 m
Target Chamber
Target Chamber
MANDALAMANDALADD neutron energy [MeV]
Co
un
t ΔE
2
5.82
)()(
keV
keVE
Ti
D ~ 2.2 m
neutron detectorneutron detector
Static Polarization of HD
B/T > 1500
Dilution Refrigerator 10 mK and 17 T (B/T = 1700)
1220
mm
170mm
70m
m
Mixing Chamber
Nb3Sn joints&Protection Circuit
NbTi joints&Switch
Main CoilCorrection Coil
Null Coil
Rough dimensions of the magnet
400mm
600m
m
550m
m
1K Pot
538m
m
16.990
16.992
16.994
16.996
16.998
17.000
17.002
17.004
17.006
17.008
17.010
- 100 - 80 - 60 - 40 - 20 0 20 40 60 80 100
0
5
10
15
z (mm)
B (T)R(mm)
150mm
500ppm
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
400 500 600 700 800 900 1000 1100 1200
0
10
20
30
40
50
60
70
80
z (mm)
B (T)R(mm)
Static Polarization of HD : DR 10 mK, 17 T solenoid
B
Adding free electrons. For B=2.5 T and T = 1 K, e- polarization = 92%
Proton relaxation time >> electron
92%
~50%
~50%
Initial concentration Needed
o-H2: < 0.02 %p-D2: < 0.1%
e-
e- Proton or Triton
Dynamic Polarization of HD or DT
Solem et al. in 1974 reach 4% H polarizationwith HD containing 4 - 5 % H2 D2
Transitions made possiblethrough microwave excitation: ~70GHz
~50%
~50%
Mass Spectrometer
Sampler Tanks
Distillator
Extraction Valves
Conclusions
Polarization looks like a MUST for future power plants.We have in Europe (and in France): ITER to study the magnetic confinementand MEGAJOULE for the inertial confinement.
The full polarization of DT fuel increases the reactivity by at least 50% and controls the reaction products direction of emission. Simulations of ICF 100%.The cost of a polarization station (107 €) is negligible compared to the cost of a reactor (1010 € for ITER).
A first question remain: D and T relaxation times during fusion process ? We have proposed a “simple” experiment to approach this question, at least for the inertial confinement: POLAF Project accepted at ILE (OSAKA) Feasibility of the experiment confirmed for D + D → 3He + n reaction which can also test the RPA features
Polarization of the fuel?DNP of HD and DT must be revisited seriously somewhere,as well as high intensity polarized D2 and T2 molecular jets.
J.-P. Didelez and C. Deutsch, « Persistence of the Polarization in a Fusion Process », LPB 29 (2011) 169
TNSA on « thick » Targets
HD Target: NMR Measurements0.85 T – 1.8 K
Back conversion at room temp.for 5 hours is 30%
HD Target: Production
Step I: HD purity monitoring – Quadrupole Mass Spectrometer
HD quality on the market ?
Step II: HD production – Distillation apparatus in Orsay
Over 3 month of ageing necessary
Distillation apparatus in Orsay
3 extraction point3 temperature probe
To mass spectrometer
Stainless Steel column filled with Stedman Packing:
Heater 1
Heater 2
- Demontrate the persistence with an ultrashort laser and a polarized HD target (HIIF2010, GSI Darmstadt, August 2010)
- Develop the Dynamic Nuclear Polarization of HD (SPIN2010, KFA Jülich, September 2010)
- DNP of DT molecules (HIIF2012, ? )
- Fusion of polarized DT at Mégajoule (20??)