1. Use of  -Ray-Generating Reactions for Diagnostics of Energetic Particles in Burning Plasma and Relevant Nuclear Data Y. Nakao Department of Applied Quantum Physics and Nuclear Engineering,Kyushu University,Japan Collaborators: H. Matsuura, N. Senmyo, K. Tsuk ida (Kyushu Univ.); M. Nakamura (Univ. of Tokyo) T. Johzaki (Osaka Univ.); V.T. Voro nchev (Moscow State Univ.) 2010 Symposium on Nuclear Data (Fukuoka, Nov. 25- 26, 2010) 1/20 Diagnostics of - Knock-on ions in Magnetically- confined burning plasma - Degenerate electrons in Laser- imploded fuel Proposal & Analysis from theoretical side

2. 1. Energetic Particle Diagnostics---Background 2/20 Energetic particles in fusion plasmas at burning stage - Products of fusion reactions - Injected beam particles - Ions accelerated by electromagnetic waves - Knock-on ions scattered by these particles Heat bulk electron and ion fluids, and Can trigger many wave-particle interactions and instabilities Diagnosing the properties of energetic particles confined in burning plasma is one of the key issues in NF research aiming at ITER. These energetic particles should be diagnosed while they are in the plasma; Measurements inside the plasma are hardly possible. Use of reaction-produced neutrals freely escaping from the plasma core Neutrons, Gamma-rays

3. 3/20 Energetic Particle Diagnostics Based on  -Ray Measurement 0.981 ( 4.44 ) MeV  -rays DT fusion plasma with a small amount of 6 Li ( 9 Be) Information on energetic triton population (α- particle confinement) Used for energetic particle diagnostics at JET experiments Kiptilyj et al., NF (2002), PRL (2004), NF (2005) Use of the D( ,  ) 6 Li reaction proposed by JAERI group Ochiai et al., RSI (2006) Use of the 6 Li(t,p) 8 Li * reaction proposed by our group Voronchev, Kukulin, Nakao, PRE (2001). Nakamura, Nakao, Voronchev et al., JPSJ (2006), NIMA (2007), FST (2008), JPFR (2007).

4. 4/20 Gamma-Ray-Generating 6 Li (t,p) 8 Li * Reaction 1) The reaction threshold is 181 keV in the centre-of-mass system 2) The excited state has a short lifetime of 12 fs. One can expect that the rate of the 0.981-MeV  -ray emission is sensitive to the population of energetic tritons. 181 keV E > 2MeV : Experimental data available E < 2MeV : Cluster folding model calculation Voronchev, Kukulin, Nakao PRE (2001) 6 Li + t → 8 Li * [ 0.981 MeV ] + p 12fs 8 Li [ gr. st. ] + γ

5. 5/20 Objective of the Work Our early speculation One could obtain information on the energy distributions of energetic tritons and  -particles by comparing the 0.981-MeV  -ray measurement with kinetic model prediction incorporating the  knock-on effect. The objective Analyze theoretically diagnostic information carried by the 0.981-MeV  -rays. Nakamura, Nakao, Voronchev et al., JPSJ (2006) T eff and n eff of knock-on tritons Confinement property of  -particles 6 Li (t, p) 8 Li* 8 Li + γ α knock-on t

6. 6/20 Kinetic Model for Energetic Ion Populations Alpha-particles & DD burn-up tritons Gaussian form Beam-injected deuterons delta-function-like form Knock-on ions knocking-up from the background Fokker-Planck equation for energetic ions Source terms Ryutov, Phys. Scr. (1992); Helander, Lisak, Ryutov, PPCF (1993) The source of 0.981-MeV  -ray Energetic tritons Alpha knock-on tritons D-beam knock-on tritons DD (burn-up) tritons

7. 7/20 Energetic Triton Populations Energy distribution functions of α knock- on tritons ( akt ), D-beam knock-on tritons ( bkt ) and DD burn-up tritons ( DDt ) f akt > f bkt, f DDt at MeV energy range. The  knock - on tritons ( akt ) are distributed up to the energy of 4 MeV. --- Fokker - Planck calculations under conditions typical of the ITER tokamak plasma

8. 8/20 Gamma-Ray Yield Comparable! The 0.981-MeV  -line reflects the presence of the  knock-on tritons. Emitted in the 9 Be( ,n) 12 C * reaction Used in JET experiments It may be used to infer T eff and n eff of the  knock-on triton population. n Li /n t = 1 % n Be /n t = 1%, T = 20 keV

9. 9/20 Gamma - Ray Emission Spectrum The spectral broadening reflects the 8 Li * spectrum. dY  /dE  can be fitted to increases monotonically with increasing T eff. The 8 Li* spectrum is governed by the  knock-on triton population. 18 keV

10. 10/20 “Analytical” Representations Fitting to the slope distribution The fitting is successfully done especially in the energy range of 0.5-2 MeV. T eff increases monotonically with increasing T.

11. 11/20 Diagnostics of the  Knock-on Triton Population experimentally determined The effective temperature T eff of the  knock-on triton could be diagnosed. Once T eff is determined, the effective concentration n eff could be assessed from experimental Y .

12. 12/20 Diagnostics of the Confinement Property of the Fusion- Born  -Particles Is the experimental (T,T eff ) plot placed onto the theoretical curve ? YES. NO. The confinement property is classical. The confinement is deteriorated. Classical Non-classical

13. Laser-imploded dense plasma 2. Degenerate Plasma Diagnostics---Background  ≧ 1000  s, kT e ≦ 1keV = Fermi energy Degree of degeneracy : Electrons should be in degenerate state. Consequence of electron degeneracy : Reduction in stopping power of plasma for energetic particles Range lengthening Measurements : Implosion experiment of CD targets at Osaka Univ. Range of D-D fusion tritons In-flight T-D reaction rate    13/20

14.  + 9 Be → 12 C * [ 2 + ;0 ] + n 12 C [ gr.st. ] +  ( 4.44 MeV ) I nfluence on I gnition & Burn history of compressed DT targets through D + T →    3.52MeV ) + n ( 14MeV ) Purpose of the Study How to diagnose the degree of electron degeneracy in compressed DT fuel --- A matter of interest We propose a new method based on  -ray measurement. DT fuel admixed with a small amount of 9 Be  -ray generating reaction  -particle heating electron thermal conduction electron - ion temperature relaxation bremsstrahlung 14/20

15. Suppose the case that The fuel would not be ignited, and Most of nuclear reactions occur around the maximum compression. Key Idea of Degeneracy Diagnostics In-flight reaction probability DT fuel admixed with a small amount of 9 Be is imploded to high densities, but Not subjected to any heating laser pulse. Reaction products carry information about compressed state of fuel. 9 Be  D T n  12 C Principal reaction Secondary reaction n Experimentally, If plasma temperatures are determined in other ways, we can assess  from P  Be -  curve by measuring the  -rays and D-T neutrons. 15/20

16. Calculated In-flight Reaction Probability P robability P  -Be has clear dependences on degeneracy parameter  and plasma temperature kT e,i. 16/20 ････ infinite plasma

17. We ignore the spatial distributions of temperature and density, and their temporal evolutions. n Be /n i = 0.1. S  = n D n T DT V = plasma volume    = time interval while the high density state is maintained ≈ R / 3C s  -Rays from Compressed Finite-Size DT/ 9 Be Pellets Yield per shot : The yield depends strongly on the plasma temperature and it seems enough for the  -rays to be detected.  R = 0.4 g/cm 2,  = 200 g/cm 3 kT e 400eV700eV1keV  0.811.422.04 P  -Be 2.21×10 -5 3.26×10 -5 4.00×10 -5  [ps] 38.128.824.1 N ,4.44MeV [ 個 /shot] 9.87×10 4 7.59×10 6 7.62×10 7 kT e 400eV700eV1keV  0.811.422.04 P  -Be 2.25×10 -5 3.35×10 -5 4.14×10 -5  [ps] 66.650.342.1 N ,4.44MeV [ 個 /shot] 9.45×10 5 7.77×10 7 7.40×10 8 17/20   R = 0.7 g/cm 2,  = 200 g/cm 3

18. The 0.981-MeV  -rays emitted in the 6 Li (t, p ) 8 Li * reaction have an important application for diagnostics of the  knock-on tritons and the  -particles in burning plasmas. 18/20 Summary (1) Summary (1) If the 0.981-MeV  -rays are detected, we can obtain information on Key parameters of  knock-on triton population (T eff, n eff ), and Confinement property of the fusion-born  -particles by comparing experimental data on the 0.981-MeV  -ray yield and emission spectrum with the theoretical slowing-down calculations.

19. We have proposed use of 9 Be (  , n   ) 12 C for diagnostics of electron degeneracy in compressed DT fuel pellets. Summary (2) and Future Works - Reaction probability P  -Be depends strongly on the degeneracy parameter  and plasma temperature kT e,i. - Experimentally, P  -Be would be determined as the ratio of the yield of 4.44-MeV  -rays from this reaction to the D-T neutron yield. - It will be possible to diagnose the degree of degeneracy, if the 4.44-MeV  - rays  and D-T neutrons can be measured. - Temporal evolutions of density-temperature profiles,  -ray and D-T neutron generation rates should be taken into account. → Analysis including implosion dynamics 19/20