13,399 research outputs found
Dynamics of ion cloud in a linear Paul trap
A linear ion trap setup has been developed for studying the dynamics of
trapped ion cloud and thereby realizing possible systematics of a high
precision measurement on a single ion within it. The dynamics of molecular
nitrogen ion cloud has been investigated to extract the characteristics of the
trap setup. The stability of trap operation has been studied with observation
of narrow nonlinear resonances pointing out the region of instabilities within
the broad stability region. The secular frequency has been measured and the
motional spectra of trapped ion oscillation have been obtained by using
electric dipole excitation. It is applied to study the space charge effect and
the axial coupling in the radial plane.Comment: Colloquium paper, 9 pages, 6 figure
Vortex dynamics and second magnetization peak in PrFeAsOF superconductor
We have studied the vortex dynamics in the PrFeAsOF
superconducting sample by dc magnetization and dynamic magnetization-relaxation
rate measurements. The field dependence of the superconducting
irreversible magnetization reveals a second magnetization peak or
fishtail effect. The large value of is an indication of moderate vortex
motion and relatively weak pinning energy. Data analysis based on the
generalized inversion scheme suggests that the vortex dynamics can be described
by the collective pinning model. The temperature dependence of the critical
current is consistent with the pinning due to the spatial variation in the mean
free path near a lattice defect ( pinning). The temperature and field
dependence of indicates a crossover from elastic to plastic vortex creep
with increasing temperature and magnetic field. Finally, we have constructed
the vortex phase diagram based on the present data.Comment: 11 pages, 8 Figures, Accepted for publication in Journal of Applied
Physic
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