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NN2012, May 31 th 2012, San Antonio, TX M. Barbui

Y ield of D-D and D- 3 He fusion reactions produced by the interaction of intense ultrafast laser pulses with molecular clusters. NN2012, May 31 th 2012, San Antonio, TX M. Barbui. Basic idea. cryogenic. CD 4 can be used in place of D 2 3 He can be added in different concentrations.

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NN2012, May 31 th 2012, San Antonio, TX M. Barbui

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  1. Yield of D-D and D-3He fusion reactions produced by the interaction of intense ultrafast laser pulses with molecular clusters NN2012, May 31th2012, San Antonio, TX M. Barbui

  2. Basic idea cryogenic CD4 can be used in place of D2 3He can be added in different concentrations 100-180 J 150-200 fs Expected fusion reactions: D + D  T (1.01 MeV) + p (3.02 MeV) (50%) D + D 3He (0.82 MeV) + n (2.45 MeV)(50%) Most of the laser energy is absorbed by the molecular clusters The electrons escape first and the clusters coulomb explode Some of the ions have enough energy to drive nuclear reactions D + 3He  4He (3.6 MeV) + p (14.69 MeV) (100%) D + T  4He (3.5 MeV) + n (14.1 MeV) (100%) D + 3He  4He (3.6 MeV) + p (14.69 MeV) (100%)

  3. Final goal • Use the yield of 14.7 MeV protons from the D-3He reaction to extract the astrophysical S factor at very low energies. • Since our medium is highly ionized and the electrons move away much faster than the ions we might be able to have a direct measurement of the bare nucleus S factor. • We used the D-D reaction as reference to extract the density of the medium. This reaction has been extensively studied in the last decades. R-matrix calculations of the cross-section of the 4He system are very stable and are supposed to be correct within a 5% for energies up to 1 MeV [Nucl. Fusion 32(1992)611]

  4. Experiment outline D ions Temperature KT Yield of 2.45MeV n from D+D->n+3He Yield of 3.02MeV p from D+D->p+T Relative concentration of D and 4He Check that adding 4He does not affect the cluster formation Phase 1 • D2 clusters • D2 clusters + 4He Phase 2 • D2 clusters + 3He • CD4 clusters + 3He D ions Temperature KT Yield of 2.45MeV n from D+D->n+3He Yield of 14.7MeV p from D+3He->p+4He Relative concentration of D and 3He The experimental yields of 14.7 MeV protons are normalized to the same atomic density of D and 3He

  5. Experimental setup 3 plastic scintillators from UT Neutron 2 Neutron 1 Neutron 3 Cryo-cooled nozzle Laser beam direction Faraday cup Proton B Proton A Proton C 3 plastic scintillators from UT Neutron 4

  6. Measured observables Temperature and the number of the energetic ions Faraday cup 4 liquid scintillators NE213 placed at different angles and 6 plastic scintillators placed at 90 degrees Yield of 2.45 MeV neutrons • Yield of 3.02 MeV protons • Yield of 14.7 MeV protons Thin (254 um) plastic scintillators BC400. 3 MeV 14.7 MeV

  7. Experimental data D-D A different density of D atoms in different shots produce those different lines. Decreasing density Same yield for 2.45MeV n and 3 MeV p No evidence of angular distribution for 2.45 MeV n or 3 MeV p

  8. Experimental data D-3He Temperature estimated from the ratio Detection limit for the Faraday cup Same density effect noticed for the D-D reaction The ratio of the two yields is independent of the atomic density and shows a smooth behavior

  9. Can we explain what we measured using the available cross-section evaluations for the D-D and D-3He reactions? • D-D 2*R=5 mm 2*r=0.5-0.8 mm Parameterizations exist for S(E) leading to values of that agree with R-matrix calculations within 1% D-D reactions may happen inside the plasma plume between two energetic D ions coming from the Maxwellian distribution of measured KT or between an energetic D ion and a D at rest outside the plasma plume.

  10. Can we explain what we measured using the available cross-section evaluations for the D-D and D-3He reactions? • D-3He D-3He reactions happen between energetic D ions coming from the measured Maxwellian distribution and 3He atoms at rest.

  11. D-D reactivity <sv> and <s> • Numerical integral with parameterization S(E) from [1] • - NACRE database [1]Nucl. Fusion 32(1992)611 • Numerical integral with parameterization S(E) from [1] • - NACRE database <sv>/v

  12. D-3He reactivity <sv> and <s> • Numerical integral with parameterization S(E) from [1] • - NACRE database [1]Nucl. Fusion 32(1992)611 • Numerical integral with parameterization S(E) from [1] • - NACRE database <sv>/v

  13. Yield ratio to calculate the ion temperature Temperature estimated from the ratio Calculated ratio 1) The yield ratio is independent of the atomic density 2) The temperatures estimated from the yield ratios agree with the temperatures measured from the time of flight 3) Therefore for each point there is an atomic density that reproduces both the yield of 2.45MeV neutrons and 14.7 protons.

  14. We calculated the density needed to reproduce the yield of 2.45 MeV neutrons from the D-D reaction. CD4 The yield of protons is calculated using : The calculated yield agrees with the measured one within the experimental errors. Our data can be described by the bare nucleus S(E) parameterization from ref [1].

  15. Experimental <s> for the D-3He reaction as a function of the temperature in the center of mass Fitting function: The parametersb1,b2,b3define the resonance at E=210 MeV and are fixed to the values of [1] The parameters a1, a2, a3are free

  16. S(E) compared with other experimental data • This work • La Cognata 05 THM “bare nucleus” • La Cognata 05 fit line • Aliotta 01 direct data • Krauss 87 direct data

  17. Summary • We measured the yield of D(D,T)p, D(D,3He)n and D(3He,a)p and the ion temperature. • The temperature can also be calculated using the ratio of the yield of D-D and D-3He reactionsThis temperature agrees with the measured one within the experimental errors. • If we use the D-D reaction to estimate the atomic density of D. We can use the experimental values of <s>D-3He to fit the parameterization of S(E)D-3He • Our values are agreement with what used so far.

  18. What is next? • Improvements of the measurement • Measure of the cluster size and the electron density using Ryleighscattering and short pulse interferometry as described in [Rev. Sci. Inst. 69(1998)3798] • Repetition of many shots without changing the nozzle conditions. • Larger dimensions of the detectors used for the 14.7MeV protons in order to decrease the statistical error. • Other reactions of can be studied with the same method

  19. Thank you for your attention! • Texas A&M: M. Barbui, K. Hagel, J.B. Natowitz, K. Schmidt, G. Giuliani. • INFN Italy: A. Bonasera(LNS), S. Kimura (LNS), M. Mazzocco(PD). • University of Texas: W. Bang, G. Dyer, H. Quevedo, E. Gaul, T. Borger, A. Bernstein, M. Martinez, M. Donovan, T. Ditmire. • ENEA Italy: F. Consoli, R. De Angelis, P. Andreoli.

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