Berlin 2001 – wissenschaftliches Programm

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A: Atomphysik

A 10: Posters Wednesday (Cooling and Trapping, Electron Scattering and Recombination)

A 10.6: Poster

Mittwoch, 4. April 2001, 12:30–15:00, AT3

Collective Resonances and Instabilities of Electrons in a Penning Trap — •Tristán Valenzuela Salazar, Debasish Biswas, Peter Paasche, and Günter Werth — Institut für Physik, Johannes Gutenberg Universität-Mainz. D-55099 Mainz. Germany

The motional spectrum of stored particles in an ideal Penning ion trap consists of three harmonic oscillations: The modified cyclotron frequency ω_c′, the axial frequency ω_z,and the magnetron frequency ω_m. Imperfections lead to couplings between the eigenfrequencies. The frequency spectrum can be observed by excitation from an additional radio-frequency field. We have performed experiments on trapped electrons and observed many linear combinations of the eigenfrequencies. Excitation of ω_z or 2ω_z revealed a double structure of the resonances which could be ascribed to the excitation of the center of mass of the electron cloud and the non-correlated motion of the individual ions. Moreover we observed instabilities of the electron confinement at operating points of the trap when ω_c′ or ω_z are integer multiples of ω_m. These observations are very similar to those made previously in Paul traps [1],[2]

[1] R. Alheit et al, Phys. Rev. A,56, 4023(1997) [2] R. Alheit et al, Int.J. Mass. Spectr. Ion Proc. 154, 155(1996)