PSFC / JA - 09 - 15 Comment on : " On higher order corrections to gyrokinetic Vlasov – Poisson equations in the long wavelength limit
نویسندگان
چکیده
A recent publication [F. I. Parra et al., Plasma Phys. Control. Fusion 50, 065014 (2008)] warned against the use of the lower order gyrokinetic Poisson equation at long wavelengths because the long wavelength, radial electric must remain undetermined to the order the equation is obtained. Another reference [W. W. Lee et al., Phys. Plasmas 16, 044506 (2009)] criticizes these results by arguing that the higher order terms neglected in the most common gyrokinetic Poisson equation are formally smaller than the terms that are left. This argument is naive and ignores that the lower order terms, although formally larger, vanish without determining the long wavelength, radial electric field. The reason for this cancellation is discussed. In addition, the origin of a nonlinear term present in the gyrokinetic Poisson equation of Ref. [F. I. Parra et al., Plasma Phys. Control. Fusion 50, 065014 (2008)] is explained. PACS numbers: 52.30.Gz, 52.65.Tt
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