Response to the Comment "Effect of the Magnetic Field on Fusion Reaction Rates"

Imazu, Shingo

doi:10.1088/0741-3335/29/7/413

Cited by 4 publications

(5 citation statements)

References 2 publications

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“…The simulation results confirm the conclusion and rule out the possibility that the enhancement of runaways is simply due to the increase in loop voltage. It may have resulted from the synergetic interaction of LHWs and IBWs since the presence of waves can enhance quasilinear diffusion of electrons in velocity space across the critical velocity for runaway generation [13,14].…”

Section: Resultsmentioning

confidence: 99%

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Enhancement of runaway production in lower hybrid current driven plasma with IBW heating in the HT-7 tokamak

Chen

Wan

Ling

et al. 2007

Plasma Phys. Control. Fusion

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Runaway production is observed to be enhanced in lower hybrid current driven (LHCD) plasmas during ion Bernstein wave (IBW) heating as compared with the LHCD only plasma in the HT-7 tokamak. The distortion of the electron distribution function is the effect of the quasilinear diffusions of two types of waves. IBWs modified the distribution function of the electrons by helping to fill the so-called lower hybrid wave (LHW) spectral gap for low parallel velocity. Thus the LHW was significantly coupled to the fast electrons produced by the IBW, and partial LHW power was absorbed on the first pass without significant n -upshift. The synergy interaction of two types of waves results in high electron parallel energy and enhanced quasilinear diffusion, which is favorable for the production of runaway electrons. This is directly related to the improvement of plasma performance in the operation mode of simultaneous injection of LHW and IBW power.

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Section: Resultsmentioning

confidence: 99%

“…The presence of waves can greatly enhance the runaway production because the quasilinear diffusion of electrons by waves can enhance the flow in velocity space across the critical velocity for runaway generation [13,14]. Waves with phase velocities comparable to the critical velocity tend to enhance the runaway production rate [15].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of runaway production in lower hybrid current driven plasma with IBW heating in the HT-7 tokamak

Chen

Wan

Ling

et al. 2007

Plasma Phys. Control. Fusion

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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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“…they run away [7]. The presence of waves can greatly enhance the runaway production because the quasilinear diffusion of electrons by waves can enhance the flow in velocity space across the critical velocity for electrons to run away [8]. LH waves with phase velocities comparable to the critical velocity tend to enhance the runaway production rate [4,9,10].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of runaway electrons in lower hybrid current drive plasmas in the HT-7 tokamak

Chen¹,

Wan²,

Lin³

et al. 2006

Plasma Phys. Control. Fusion

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In lower hybrid current drive (LHCD) plasmas with non-zero loop voltage, the fast electron tail can act as a seed population of runaways. The runaways are found to be enhanced in the presence of lower hybrid (LH) waves when the fast electron tail extends above the critical velocity for electrons to run away. In runaway discharges, the LH waves may suppress runaway electrons due to the drop in the electric field linked to the non-inductive current drive. In this paper, the behaviour of runaway electrons in an extensive range of LHCD plasmas is presented.

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Response to the Comment "Effect of the Magnetic Field on Fusion Reaction Rates"

Cited by 4 publications

References 2 publications

Enhancement of runaway production in lower hybrid current driven plasma with IBW heating in the HT-7 tokamak

Enhancement of runaway production in lower hybrid current driven plasma with IBW heating in the HT-7 tokamak

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

Dynamics of runaway electrons in lower hybrid current drive plasmas in the HT-7 tokamak

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