Dans ce travail on dtudie d'abord les dquilibres toroidaux les plus ge'ne'raux au voisinage d'un axe magnetique, ligne caracteVistique dans la topologie toroi'dale. Dans ce but, on utilise un systeme de coordonne'es triorthogonales lie" a l'axe magnetique d^fini a l'aide de ses coordonne'es intrinseques: R{s) et T(s). Les re"sultats des calculs d'^quilibre montrent que toutes choses 6gales par ailleurs, il n'existe plus d'dquilibre possible en ge"ne"ral lorsque Tangle de transformation rotationnelle sur l'axe magne'tique « c o s'approche d'un multiple entier de 2 n. On donne les deVeloppements des quantitds physiques a l'^quilibre jusqu'au troisieme ordre. On d^duit de ces proprie'te's un classement des e'quilibres toroidaux, et des exemples sont traites.Dans la deuxieme partie, on e"tudie la stability de ces e'quilibres vis-a-vis des de"placements localises. Les resultats indiquent des plages de stabilites pour des configurations caracte'rise'es par t c o/27tft(fc. Un exemple simple de stellarator droit est traite" et fournit des conditions d'e"quilibre et de stability caracte'risdes par des /3 C d'^quilibre et de stability. D'autres exemples montrant explicitement l'effet de la courbure de l'axe magne'tique sont traite's dans la re"f. 3.
L'analyticite nous oblige a poser(20) Nous ecrirons les autres developpements comme suit N (cont ! d) 65-821 Ms 133
On 2001 April 15, the Nançay radioheliograph observed fast-moving, expanding loops in images taken in the wavelength range between 164 and 432 MHz. We were able to follow the progression of the radio loops, starting from a few tenths to more than 1 R above the solar limb, with a time cadence of order seconds. The loops seen in radio agree very well with the features of the coronal mass ejection (CME) seen later, more than 2.5 R above the limb, in white-light images by the Large Angle Spectrometric Coronagraph (LASCO) experiment on board the Solar and Heliospheric Observatory (SOHO) spacecraft. The event is well associated with an energetic electron event seen by the Electron, Proton, and Alpha Monitor (EPAM ) experiment on board the Advanced Composition Explorer (ACE ) spacecraft. A detailed transport model for the electrons shows that, not only the inferred onset at the Sun, but also the duration of the particle release, are similar for the radio loop and the in situ electron event detected near the Earth.
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