Negative-energy perturbations in circularly cylindrical equilibria within the framework of Maxwell-drift kinetic theory
Φόρτωση...
Ημερομηνία
Συγγραφείς
Throumoulopoulos, G. N.
Pfirsch, D.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Physical Review E
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
The conditions for the existence of negative-energy perturbations (which could be nonlinearly unstable and cause anomalous transport) are investigated in the framework of linearized collisionless Maxwell-drift kinetic theory for the case of equilibria of magnetically confined, circularly cylindrical plasmas and vanishing initial field perturbations. For wave vectors with a nonvanishing component parallel to the magnetic field, the plane equilibrium conditions (derived by Throumoulopoulos and Pfirsch [Phys Rev. E 49, 3290 (1994)]) are shown to remain valid, while the condition for perpendicular perturbations (which are found to be the most important modes) is modified. Consequently, besides the tokamak equilibrium regime in which the existence of negative-energy perturbations is related to the threshold value of 2/3 of the quantity eta(nu) = partial derivative InTnu/partial derivative InNnu, a new regime appears, not present in plane equilibria, in which negative-energy perturbations exist for any value of eta(nu). For various analytic cold-ion tokamak equilibria a substantial fraction of thermal electrons are associated with negative-energy perturbations (active particles). In particular, for linearly stable equilibria of a paramagnetic plasma with hat electron temperature profile (eta(e) = 0), the entire velocity space is occupied by active electrons. The part of the velocity space occupied by active particles increases from the center to the plasma edge and is larger in a paramagnetic plasma than in a diamagnetic plasma with the same pressure profile. It is also shown that, unlike in plane equilibria, negative-energy perturbations exist in force-free reversed-field pinch equilibria with a substantial fraction of active particles. The present results, in particular the fact that a threshold value of eta(nu), is not necessary for the existence of negative-energy perturbations, enhance even more the relevance of these modes.
Περιγραφή
Λέξεις-κλειδιά
guiding-center theories, plasma edge turbulence, vlasov equilibria, waves, conservation, formulation
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://A1996UA37100099
http://pre.aps.org/abstract/PRE/v53/i3/p2767_1
http://pre.aps.org/abstract/PRE/v53/i3/p2767_1
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών