arXiv subjects

Adrien Poindron

Publications and source records attributed to Adrien Poindron.

3 recordsLinked to original sources

arXiv2023

Heating rate in a linear quadrupole trap

In radio-frequency trap, the temperature of ion ensembles converges towards a hot equilibrium due to radio-frequency heating. This effect is detrimental to the stability of trapped ensembles and is the justification of cooling. The intensity of this radio-frequency heating increases with the amplitude of the radio-frequency field $q_x$. Using an analytical empirical formula, we show that the lifetime of the ion ensemble $t_0$ under cold condition increases with $q_x$ according to a power law $t_0\propto q_x^A$, and does not vary significantly for the several ion quantities $N$ tested. The temperature of the explosive onset $B$ decreases linearly with $q_x$. We also show that non-linear instabilities due to trapping parameters decreases $t_0$ and $B$, and produce a local increase of heating rate for certain temperature ranges.

physics.atom-ph↗

arXiv2023

Thermal bistability in laser-cooled trapped ions

The non-linear dynamics of large ion clouds ($N \geq 256 $ ions) trapped in radio-frequency traps and coupled to laser-cooling give rise to a bistable behaviour of the temperature. Numerical simulations of the free evolution of a large three-dimensional spherical cloud is used to characterise how the oscillating field amplitude and the ion number control the rf heating rate and the switching between the two stable states. We show that the heating rate does not significantly depends on the ion number but strongly depends on the oscillating field. This exhibits the major role played by the density of the ensemble. The competition between the radio-frequency heating and the laser cooling is also discussed. They are used to design scenarii to take advantage of the threshold effect to detect and quantify perturbations by an intruder.

physics.atom-ph↗

arXiv2021

Non-destructive detection of large molecules without mass limitation

The problem for molecular identification knows many solutions which include mass spectrometers whose mass sensitivity depends on the performance of the detector involved. The purpose of this article is to show by means of molecular dynamics simulations, how a laser-cooled ion cloud, confined in a linear radio-frequency trap, can reach the ultimate sensitivity providing the detection of individual charged heavy molecular ions. In our simulations, we model the laser-cooled Ca + ions as two-level atoms, confined thanks to a set of constant and time oscillating electrical fields. A singly-charged molecular ion with a mass of 10 6 amu is propelled through the ion cloud. The induced change in the fluorescence rate of the lather is used as the detection signal. We show that this signal is due to a significant temperature variation triggered by the Coulombian repulsion and amplified by the radio-frequency heating induced by the trap itself. We identify the optimum initial energy for the molecular ion to be detected and furthermore, we characterize the performance of the detector for a large range of confinement voltages.

physics.ins-det↗