Effect of the magnetic field on the collision frequencies for fusion reactions at low energies

Imazu, Shingo

doi:10.1088/0741-3335/28/6/002

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…The importance of the magnetic field for the collision frequency of helium atoms is given by the value of the product of the mean collision time between helium ions and protons τ αH and gyration frequency of helium ions ω α (Mestel 2003, p. 18 therein;Braginskij 1963;Imazu 1986). The mean collision time τ αH is given by…”

Section: Discussionmentioning

confidence: 99%

Multicomponent radiatively driven stellar winds

Krtička¹,

Kubát

Groote

2006

A&A

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We study the possibility of the helium decoupling in the stellar wind of σ Ori E. To obtain reliable wind parameters for this star we first calculate NLTE wind model and derive wind mass-loss rate and terminal velocity. Using corresponding force multipliers we study the possibility of helium decoupling. We find that helium decoupling is not possible for realistic values of helium charge (calculated from NLTE wind models). Helium decoupling only seems possible for a very low helium charge. The reason for this behavior is the strong coupling between helium and hydrogen. We also find that frictional heating becomes important in the outer parts of the wind of σ Ori E due to the collisions between some heavier elements and the passive components -hydrogen and helium. For a metallicity ten times lower than the solar one, both hydrogen and helium decouple from the metals and may fall back onto the stellar surface. However, this does not explain the observed chemical peculiarity since both these components decouple together from the absorbing ions. Although we do not include the effects of the magnetic field into our models, we argue that the presence of a magnetic field will likely not significantly modify the derived results because in such case model equations describe the motion parallel to the magnetic field.

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Section: Discussionmentioning

confidence: 99%

Multicomponent radiatively driven stellar winds

Krtička¹,

Kubát

Groote

2006

A&A

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“…It was claimed that relatively weak magnetic fields reduce collision rates of nuclear reactions by a factor of two through alignments of directions in which charged nuclei can move [87,88]. The claim is, however, wrong [89,90] since it was based on a completelymistaken treatment of 2D space perpendicular to the field direction, and cases of B = 0 and B = 0 are not treated consistently.…”

Section: Appendix B: Effect On Nuclear Reaction Ratesmentioning

confidence: 99%

Updated constraint on a primordial magnetic field during big bang nucleosynthesis and a formulation of field effects

Kawasaki

Kusakabe

2012

Phys. Rev. D

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A new upper limit on the amplitude of primordial magnetic field (PMF) is derived by a comparison between a calculation of elemental abundances in big bang nucleosynthesis (BBN) model and the latest observational constraints on the abundances. Updated nuclear reaction rates are adopted in the calculation. Effects of PMF on the abundances are consistently taken into account in the numerical calculation with the precise formulation of changes in physical variables. We find that abundances of 3 He and 6 Li increase while that of 7 Li decreases when the PMF amplitude increases, in the case of the baryon-to-photon ratio determined from the measurement of cosmic microwave background radiation. We derive a constraint on the present amplitude of PMF, i.e., B(0) < 1.5 µG [corresponding to the amplitude less than 2.0 × 10 11 G at BBN temperature of T = 10 9 K] based on the rigorous calculation. PACS numbers: 26.35.+c, 98.62.En, 98.80.Es, 98.80.Ft * kusakabe@icrr.u-tokyo.ac.jp 1 I. INTRODUCTIONPrimordial nucleosynthesis, or big bang nucleosynthesis (BBN), has been assumed [1] to occur through complicated nonequilibrium processes. It involves many reactions including radiative neutron capture reactions [1-3] and weak interactions converting protons and neutrons to each others [4] as well as relativistic quantum statistics [5]. In BBN, only D, 3 He, 4 He and 7 Li can be produced in significant amounts [6], and yields of heavier elements are generally expected to be small [7,8]. The BBN model predicts the relic of a dense hot radiation [3,9] to be observed as cosmic microwave background radiation (CMBR) today [10].The BBN has been studied over a long period, and the theory is now precisely structured (e.g., [6,). The simplest, standard BBN (SBBN) model is characterized by one parameter, i.e, baryon-to-photon number ratio η with the fixed number of light neutrino species of N = 3. The η value is constrained precisely with data of the Wilkinson Microwave Anisotropy Probe (WMAP) [39-41]. The SBBN model prediction of light element abundances for the WMAP η value is rather consistent with primordial abundances inferred from observations. There is, however, a discrepancy between the predicted and observed primordial abundances of 7 Li. The SBBN predicts a 7 Li abundance which is a factor of 2.4 − 4.3 times higher [42] than the observationally deduced abundance. Possible solutions to this discrepancy have been proposed (e.g. [43] and references therein).O'Connel and Matese [44] have estimated the neutron β-decay rate in the presence of a strong magnetic field, and suggested that an increase in the rate due to primordial magnetic fields (PMFs) decreases 4 He abundance. Greenstein [45] subsequently suggested that the energy of PMFs enhances the expansion rate of the universe, and it tends to increase the 4 He abundance rather than decrease it as suggested in Ref. [44]. Matese & O'Connel [46] then performed a detailed investigation on the PMF effects on BBN, and concluded that the effect through the expansion rate is predominant over ...

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Effect of the magnetic field on fusion reaction rates

Jarvis

Imazu

1987

Plasma Phys. Control. Fusion

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A RECENT paper (IMAZU, 1986) purports to demonstrate that the fusion reaction rates in high temperature plasmas decrease as the strength of the applied magnetic field rises. The magnitudes of the claimed effect is significant, the B = 5T rate being only half the B = 0 rate.If we leave aside the question of the reacting particles being spin polarized, then it is well known (JANCEL and KAHAN, 1966) that a magnetic field has no effect whatever on the velocity distribution of particles in thermal equilibrium, hence it can have no effect on the fusion reaction rate.The error in the paper by Imazu can be found in equation 7 where a geometrical model of the particle orbits has been misinterpreted.

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Effect of the magnetic field on the collision frequencies for fusion reactions at low energies

Cited by 6 publications

References 3 publications

Multicomponent radiatively driven stellar winds

Multicomponent radiatively driven stellar winds

Updated constraint on a primordial magnetic field during big bang nucleosynthesis and a formulation of field effects

Effect of the magnetic field on fusion reaction rates

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