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| DC Field | Value | Language |
|---|---|---|
| dc.contributor.author | Throumoulopoulos, G. N. | en |
| dc.contributor.author | Pfirsch, D. | en |
| dc.date.accessioned | 2015-11-24T18:40:07Z | - |
| dc.date.available | 2015-11-24T18:40:07Z | - |
| dc.identifier.issn | 1063-651X | - |
| dc.identifier.uri | https://olympias.lib.uoi.gr/jspui/handle/123456789/17562 | - |
| dc.rights | Default Licence | - |
| dc.subject | guiding-center theory | en |
| dc.subject | drift kinetic-theory | en |
| dc.subject | vlasov equilibria | en |
| dc.subject | maxwell-vlasov | en |
| dc.subject | waves | en |
| dc.subject | plasma | en |
| dc.subject | modes | en |
| dc.subject | formulation | en |
| dc.subject | framework | en |
| dc.subject | tokamak | en |
| dc.title | Negative-energy perturbations in cylindrical equilibria with a radial electric field | en |
| heal.type | journalArticle | - |
| heal.type.en | Journal article | en |
| heal.type.el | Άρθρο Περιοδικού | el |
| heal.identifier.secondary | <Go to ISI>://A1997YH16800044 | - |
| heal.language | en | - |
| heal.access | campus | - |
| heal.recordProvider | Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών | el |
| heal.publicationDate | 1997 | - |
| heal.abstract | The impact of an equilibrium radial electric field E on negative-energy perturbations (NEP's) in cylindrical equilibria of magnetically confined plasmas is investigated within the framework of Maxwell-drift kinetic theory. It turns out that for wave vectors with a nonvanishing component parallel to the magnetic field, the conditions for the existence of NEP's in equilibria with E=0 [G. N. Throumoulopoulos and D. Pfirsch, Phys. Rev. E 53, 2767 (1996)] remain valid, while the condition for the existence of perpendicular NEP's, which are found to be the most important perturbations, is modified. For \e(i) phi\approximate to T-i, a scaling which is satisfied in the edge region of magnetic confinement systems (phi is the electrostatic potential), the impact of E on perpendicular NEP's depends on the value of T-i/T-e, i.e., (a) for T-i/T-e < beta(c) approximate to P/(B-2/8 pi) (P is the total plasma pressure) the electric field does not have any effect; and (b) for T-i/T-e > beta(c), a case which is of operational interest in magnetic confinement systems, the existence of perpendicular NEP's depends on e(nu)E, where e(nu) is the charge of the particle species nu. In the latter case, for tokamaklike equilibria and H mode parameters pertaining to the plasma edge two regimes of NEP's exist. In the one of them the critical value 2/3 of eta(i) = partial derivative lnT(i)/partial derivative lnN(i) plays a role in the existence of ion NEP's, as in equilibria with E=0, while a critical value of eta(e) does not occur for the existence of electron NEP's. However, E has a ''stabilizing'' effect on both particle species in that (a) the portion of particles associated with NEP's (active particles) is nearly independent of the plasma magnetic properties, i.e., it is nearly the same in a diamagnetic plasma and in a paramagnetic plasma, while in equilibria with E=0 this portion is much larger in a paramagnetic plasma than in a diamagnetic plasma; and (b) the fraction of active particles can decrease from the plasma interior to the edge, e.g., for the case of electron NEP's in an equilibrium of a diamagnetic plasma, contrary to equilibria with E=0. In particular, the fraction of active electrons decreases with increasing eta(e) and for eta(e) > eta(o) approximate to 4/3 the electric field stabilizes the electrons, in that the fraction of active electrons becomes smaller than the one corresponding to equilibria with E=0. In addition, E has similar stabilizing effects on electron NEP's in stellaratorlike equilibria with pressure profiles identical to those of tokamaklike equilibria, while it results in an increase of the fraction of active ions in reversed-field-pinchlike equilibria. The present results indicate that the radial electric field reduces the NEP's activity in the edge region of tokamaks and stellarators, the reduction of electron NEP's being more pronounced than that of ion NEP's. | en |
| heal.journalName | Physical Review E | en |
| heal.journalType | peer reviewed | - |
| heal.fullTextAvailability | TRUE | - |
| Appears in Collections: | Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά) | |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| throumoulopoulos-1997-Negative-energy perturbations in cylindrical equilibria with a radial electric field.pdf | 262.02 kB | Adobe PDF | View/Open |
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