Clear imaging of ion cloud rotation using a combination of a thin metal wire, a micro-channel plate attached to a phosphor screen, and a high-speed camera

Abstract

To obtain the radial profile of the ion velocity u i( r) of a pure ion cloud, for the first time, we successfully captured images of the shadow of a thin rotating metal wire by scanning the pure ion cloud using a combination of a micro-channel plate attached to a phosphor screen and a high-speed camera. It appears that the rotation angle of the measured metal wire agrees with the estimated value based on the theory of two-dimensional equilibria of non-neutral plasmas, rather than the magnetron motion of a single ion confined in a Penning trap. This method may be utilized as a tool to experimentally investigate u i( r, t) in electrically non-neutral two-fluid plasmas, which is an unexplored topic in advanced plasma physics.

Confinement Experiments of Pure Ion and Electron Plasmas in a Nested Trap

“…Here, the vertical shadow in the image is the shadow of a wire [15] that is installed inside the vessel when this series of experiments is performed. The wire is installed to mea- sure the azimuthal rotation velocity v σθ of the Li + or e − plasma.…”

Spatial and Temporal Detection of Ions Ejected from Coulomb Crystals

“…When interfaced with a CCD camera, ion positions can be recorded as a function of time�with this approach widely used in velocity map imaging studies. 27−29 Variations of the technique have been employed in the detection of Li + ion clouds to obtain radial ion velocity profiles, 30 in addition to the study of buffer-gas cooling effects on non-neutral plasmas (containing 10 7 ions) in linear Paul traps. 31 Advances in camera technology have recently enabled the simultaneous measurement of both the position and timing of ion signals, achieving exceptional time resolution while maintaining position sensitivity.…”

“…The coupling of microchannel plates (MCPs) with a phosphor screen allows for the simultaneous recording of ion flight times and positions with the channel-specific electron cascade generated by the MCPs, inducing phosphorescence on the screen. When interfaced with a CCD camera, ion positions can be recorded as a function of timewith this approach widely used in velocity map imaging studies. − Variations of the technique have been employed in the detection of Li + ion clouds to obtain radial ion velocity profiles, in addition to the study of buffer-gas cooling effects on non-neutral plasmas (containing 10 7 ions) in linear Paul traps …”

“…When interfaced with a CCD camera, ion positions can be recorded as a function of time—with this approach widely used in velocity map imaging studies. 27 − 29 Variations of the technique have been employed in the detection of Li + ion clouds to obtain radial ion velocity profiles, 30 in addition to the study of buffer-gas cooling effects on non-neutral plasmas (containing 10 7 ions) in linear Paul traps. 31 …”