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Polarized Fusion
by Giuseppe Ciullo INFN and University of Ferrara
for Ralf Engels JCHP / Institut für Kernphysik, FZ Jülich
21.10.2014
Nuclear Fusion with Polarized Particles
2
The first three reactor generations, organized according to relative energy (temperature) requirement for fusion.
Polarized Fusion
Total cross section Energy production: 1. Generation: D + T 4He + nHighest cross section at lowest temperature
2. Generation: D + D t + p or 3He + nFuel everywhere available
3. Generation 3He + D 4He + pNeutron lean reactor if D+D suppressed
(More fusion reactions are possible !)
Up to now: The D + D reactions are used in scientific tokomaks (ITER is optimized for DT!)
3
Can the total cross section of the fusion reactionsbe increased by using polarized particles ?
3He + d 4He + p
t + d 4He + n
J = 3/2 + / s-wave dominated (~96%)
H. Paetz gen. Schieck, Eur. Phys. J. A 44, 321-354 (2010)
Polarized Fusion
More details in A. Sandorfi’s talk and
Factor: ~1.5 at 107 keV
Factor: ~1.5 at 430 keV
[Ch. Leemann et al., Helv. Phys. Acta 44, 141 (1971)]
4
What is the advantage for fusion reactors ?
Polarized Fusion
Laser Pellet target (DT pellets)
(Berkeley, Orsay, Darmstadt, …)
1.) Inertial Fusion (Laser induced fusion)
5
What is the advantage for fusion reactors ?
Calculation by M. Temporal et al. for the „Megajoule“ Project
Polarized Fusion
M. Temporal et al.; “Ignition conditions for inertial confinement fusion targets with polarized DT fuel” Nucl. Fusion 52 (2012) 103011
s DT pol = d s DT unpol
6
Can the trajectories of the ejectiles be controlled by using polarized particles ?
Polarized Fusion
Total cross sectionUnpolarized differential cross section
7
1st generation reactor:polarized fuel helps to optimize fusion reactors
D + T (3He + D) polarized fuel1st
*
*
* D and T spin || to the confinement field: a and n emitted as sin2 q respect to B
* D spin ┴ to the confinement field
and T unpolarized: no influence on cross section, but the reaction products follow (1+3cos2 q).
Confirmed on mirror reaction 3He(d,p)4He [Ch. Leeman et al Helv. Phys. Acta 44 (1971) 141]
8
D + D reactors
D + D → T + p 50% (no n)→ 3He + n 50%(*)
D + T can fuses (n)3He does not contribute at the ignition energy of D-D
D ↑ + D ↑ spin dependent cross section (data set very poor), at low energy (electron screening ?).
2nd
D + 3He → 4He +p ? Can we have neutron free reactor?
3rd
If we suppress or reduce D-D fusion,we could have neutron free or lean reactors?
9
Spin allows to enhance or suppress reaction channels
Neutron lean fusion reactor D -3He
D↑ (d ↑ p) T and D↑ (d ↑ n) 3He suppressed by choosing deuteron spin parallel each others
S 1 1 0 5S2 Quintet State Suppressed
S 1 -1 0 1S0 Singlet state allowed
D↑ D↑ 4He*
10
Polarized Fusion
Deltuva in Nuclear fusion with polarized nucleonsTrento 14-15 Nov 2013
11
Which questions must be solved ?
1.) Dependence of the total cross section from the polarization for all fusion reactions.
Polarized Fusion
d + dt + p
3He + n
Can cross sections be increased ?
Can neutrons be suppressed ?Can the trajectories of the neutronsbe controlled?
Reaction is not s-wave dominated !
12
Spins of both deuteronsare aligned:
Only pz(qz) and pzz(qzz) ≠ 0
Only beam is polarized:
(pi,j ≠ 0, qi,j = 0)σ(ϴ,Φ) = σ0(ϴ) · {1 + 3/2 Ay(ϴ) py
+ 1/2 Axz(ϴ) pxz
+ 1/6 Axx-yy(ϴ) pxx-zz
+ 2/3 Azz(ϴ) pzz }
Polarized Fusion
13
The Experimental Setup at PNPI
ABS from the SAPIS project:(after upgrade)~ 4 ∙ 1016 a/s→ ~ 2 ∙ 1011 a/cm2
POLIS (KVI, Groningen)
Ion beam: I ≤ 20 μA
→ 1.5 ∙ 1014 d/s( Ebeam ≤ 32 keV )
dd-fusion polarimeter
LSP from POLIS
LSP from the SAPIS project
Luminosity: 3 ∙ 1025 /cm2 s
→ count rate: ~ 40 /h
→ 2 month of beam time
Detector Setup:4π covered by - large pos. sens. Detectors- (~ 500 single PIN diodes ?)
ABS from Ferrara:
~ 6 ∙ 1016 a/s
→ ~ 3 ∙ 1011 a/cm2
Luminosity: 4.5 ∙ 1025 /cm2 s
→ count rate: ~ 60 /h
→ 1 month of beam timeP. Kravtsov in Nuclear fusion with polarized nucleonsTrento 14-15 Nov 2013
14
POLIS and Ferrara ABS @ PNPI
← POLIS →
← ABS from Fe
15
Which questions must be solved ?
1.) Dependence of the total cross section from the polarization for all fusion reactions. (d+d is underway) 2.) Polarization conservation in the different plasmas ? a.) Magnetic confinement:
Details in the next talk by Andrew Sandorfi(US-Patent by H. Greenside, R. Budny and D. Post on a special surface
for polarization conservation on the wall !)
b.) Inertial Fusion (Laser induced): - J.P. Didelez and C. Deutsch; 2011 Laser and Particle
Beams 29 169. - M. Büscher (FZJ / Uni. Düsseldorf)
„Laser Acceleration“
Polarized Fusion
16
Laser Acceleration
~ 100 GV/m ~ 100 GV/m
Proton rich dot20x20x0.5 μm
108 protons at 1.5 MeV 1011 protons up to 10 MeV
Laser Acceleration of pol. 3He2+ ions from pol. 3He gas jets
A. Holler in Nuclear fusion with polarized nucleons Trento 14-15 Nov 2013
17
Which questions must be solved ?
1.) Dependence of the total cross section from the polarization for all fusion reactions. 2.) Polarization conservation in the different plasmas ?
3.) How to produce polarized fuel ?- HD targets are available (10 mK, ~15 T -> see next
talk )
-> frozen spin DT targets possible ??
Gaseous fuel a.) pol. 3He is available („Laser-pumping“) b.) pol. T will be possible with a similar method c.) pol. D ???
Polarized Fusion
18
PIT @ ANKE/COSY
Main parts of a PIT:• Atomic Beam Source
• Target gas
hydrogen or deuterium• H/D beam intensity (2 hyperfine states)
8.2 . 1016 / 6 . 1016 atoms/s• Beam size at the interaction point
σ = 2.85 ± 0.42 mm• Polarization for hydrogen/deuterium
PZ = 0.89 ± 0.01
PZ = -0.96 ± 0.01
Pz = + 0.88 ± 0.01 / - 0.91 ± 0.01
Pzz = - 1.71 ± 0.03 / + 0.90 ± 0.01
• Lamb-Shift Polarimeter• Storage Cell
19
Polarized H2/D2 Molecules
lim 0.5B
R
Nuclear Polarization of Hydrogen Molecules from
Recombination of Polarized Atoms
T.Wise et al., Phys. Rev. Lett. 87, 042701 (2001).
2
0 exp cBR R n
B
Measurements from NIKHEF, IUCF, HERMES show that recombined molecules retain fraction of initial nuclear
polarization of atoms!
polarized
unpolarized
Pm = 0.5
Naïve model
Is there a way to increase
Pm (surface material, T, B etc)?
20
The SetupISTC Project # 1861 PNPI, FZJ, Uni. Cologne
DFG Project: 436 RUS 113/977/0-1
21
Polarized H2 Molecules
Pm = - 0.84 ± 0.02 n = 277 ± 31
Protons: Pm = - 0.81 ± 0.02 n = 174 ± 19 c = 0.993 ± 0.005
Measurements on Fomblin Oil (Perfluorpolyether PFPE)
HFS 3 (Pa = - 0.93)
H2 - Ions: +
TCell = 100 K
Expected max. molecular polarizaton Pm= - 0.87)
R. Engels et al. RSI 85 (2014) 103505
22
Which questions must be solved ?
1.) Dependence of the total cross section from the polarization for all fusion reactions. 2.) Polarization conservation in the different plasmas ?
3.) How to produce polarized fuel ?- HD targets are available (10 mK, ~15 T -> see next talk )
-> frozen spin DT targets possible ??
Gaseous fuel
a.) pol. 3He is available („Laser-pumping“) b.) pol. T will be possible with a similar method c.) pol. D ??? => new ideas are welcome !!!!
Polarized Fusion