Hannover 2003 – scientific programme

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A: Atomphysik

A 11: Postersitzung 1

A 11.5: Poster

Tuesday, March 25, 2003, 16:00–18:30, Poster

Individual and Center-of-Mass Oscillations, Fractional Frequencies and Threshold behaviour in the Axial Oscillation of Electrons in a Penning Trap — •C. Angelescu, G. Tommaseo, P. Paasche, T. Valenzuela, and G. Werth — Universität Mainz, Institut für Physik, 55099 Mainz

The ion motion in Penning trap can be regarded as a system of harmonic oscillators. It offers the possibility to study anharmonic characteristics when parametrically excited by an external periodical driving force. In our experiment we excited a stored electron cloud in a Penning trap by applying an additional quadrupole rf-field to the endcaps. We observed phenomena such as individual and center-of-mass oscillations of an electron cloud and fractional frequencies to the axial oscillations which show a characteristic threshold behaviour. This can be explained with the existence of a damping mechanism affecting the electron cloud; a minimum value of the excitation amplitude is required in order to overcome the damping. The threshold amplitude shows a different behaviours for odd or even fractions of the oscillation frequency.

[1] Landau and Lifshitz, Mechanics(Pergamon, Oxford, 1960)

[2] Razvi et al., Phys. Rev. A 58, R 34 (1998)