Penning阱中离子运动的分析

根据Penning离子阱结构及电磁场分布特点,列出阱内离子运动方程并进行求解,对其中沿z轴运动和在xy平面上的运动进行详细分析,最后得到比荷为m/q的离子在Penning阱内的运动为沿磁场方向的简谐振动、绕磁感线旋转的回旋运动和垂直于z轴及径向绕z轴的漂移运动的叠加.     

Recent developments in ion detection techniques for Penning trap mass spectrometry at TRIGA-TRAP

The highest precision in the determination of nuclear and atomic masses can be achieved by Penning trap mass spectrometry. The mass value is obtained through a measurement of the cyclotron frequency of the stored charged particle. Two different approaches are used at the Penning trap mass spectrometer TRIGA-TRAP for the mass determination: the destructive Time-Of-Flight Ion Cyclotron Resonance (TOF-ICR) technique and the non-destructive Fourier Transform Ion Cyclotron Resonance (FT-ICR) method. New developments for both techniques are described, which will improve the detection efficiency and the suppression of contaminations in the case of TOF-ICR. The FT-ICR detection systems will allow for the investigation of an incoming ion bunch from a radioactive-beam facility on the one hand, and for the detection of a single singly charged ion in the Penning trap on the other hand.     

Temperature measurement of a single ion in a Penning trap

The present work is concerned with the association of a temperature to a single ion stored in a Penning ion trap. Several methods are described which allow to determine the temperature by measurements of the ions cyclotron and axial trapping frequencies. Recent results of a measurement on a hydrogen-like carbon ion ¹²C^{5 +} by use of mode coupling are presented and possible further applications are discussed.Received: 8 July 2004, Published online: 6 December 2004PACS: 07.20.-n. Thermal instruments and apparatus - 07.20.Dt. Thermometers - 42.50.Lc Quantum fluctuations - 42.50.Vk Mechanical effects of light on ions     

Calculating damping effects for the ion motion in a Penning trap

In this note a simple idea is suggested to calculate the effect of damping on the ion motion in a Penning trap. The analysis is restricted to the experimentally important special case that the axial motion (z-direction) is not coupled to that in the xy-plane, so that both motions can be treated separately. The method views the cyclotron frequency ω_c as a complex variable that can be continued analytically from real values (undamped case) into the complex plane. The power of the approach becomes obvious in connection with advanced problems such as the calculation of line profiles for quadrupole excitation.     

Investigation of ion dynamics in a Penning trap using a pulse-probe technique

We demonstrate a pulse-probe method for measuring the ion-cloud rotation frequency in a Penning trap. We show that it is useful over a range of parameters not accessible to the photon correlation method of Dholakia et al. [1]. In particular, the pulse-probe method works for larger clouds than the photon-correlation method. We show that the pulse-probe method measures the space-charge-shifted frequency and gives us the optical pumping times within clouds. Furthermore, we show that, for Mg⁺ ions, it is capable of measuring much higher degrees of space-charge shift than the photon-correlation method. Improvements to the method may enable its use in measuring diffusion rates for ions in clouds.     

Electronic detection of a single particle in a coplanar-waveguide Penning trap

We present a detailed model of the electronic detection of a single particle in a coplanar-waveguide Penning trap. The detection signal is the electric current induced upon the trap’s surface by the charged particle’s motion. In contrast to three-dimensional hyperbolic or cylindrical traps, the cyclotron and magnetron motions can be detected, excited or coupled to the axial motion without segmenting any of the trap’s electrodes. We calculate the effective coupling displacement for different electrodes. This determines the detection signal and resistive cooling time constant for each component of the ion’s motion. We discuss the practical implementation of the electronic detection for a single electron and a single proton.     

Penning阱中Hn+团簇离子的检测与确认

报道了在Penning阱中检测与确认Hn 团簇离子的方法,介绍了离子在阱中的运动,重点分析了离子存储条件、离子的产生与探测、离子信号的放大与检波以及离子谱的分辨.     

Penning阱中离子谱的优化及Hn^＋离子的分析

根据Penning阱存储离子的探测原理,系统分析了阱内离子信号及信号本身的噪声、实验仪器及探测电路的噪声干扰,采用适当的品质因数和电子束流,得到较高信噪比和分辨率的离子谱.并对Hn+离子的形成机制和结构进行了分析.     

Theory and simulation of ion Coulomb crystal formation in a Penning trap

Ion Coulomb crystals (ICCs) are formed by laser-cooled ions in both radio-frequency and Penning traps. In radio-frequency traps, the crystals are generally stationary. In Penning traps, ICCs always rotate. The frequency of rotation is often set by an applied rotating wall drive that forces the crystal to rotate at the same frequency as the drive. In the absence of any applied rotating or oscillating fields, ICCs in a Penning trap can be in stable equilibrium with a range of rotation frequencies. The density and shape of the crystal adjust with the rotation frequency to ensure that equilibrium is reached. Here, we show that the parameters of the radial laser-cooling beam determine the rotation frequency of a small crystal in a Penning trap when no driving fields are present. We demonstrate, using an approximate theoretical treatment and realistic simulations, that the crystal rotation frequency is independent of the number of ions and the trap parameters, so long as the crystal radius remains smaller than the cooling laser beam waist. As the rotation frequency increases, the crystal eventually becomes a linear string, at which point it is no longer able to adjust its density. Instead, a small amplitude vibration in the zigzag mode of oscillation manifests itself as a rotation of the crystal at a fixed frequency that depends only on the applied trap potential.     

Dynamics of a single ion in a perturbed Penning trap. Sextupolar perturbation

In the frame work of classical mechanics, we study the nonlinear dynamics of a single ion trapped in a Penning trap perturbed by an electrostatic sextupolar perturbation. The perturbation is caused by a deformation in the configuration of the electrodes. By using a Hamiltonian formulation, we obtain that the system is governed by three parameters: the z-component of the canonical angular momentum P _φ - which is a constant of the motion because the perturbation we assume is axial-symmetric -, the parameter δ that determines the ratio between the axial and the cyclotron frequencies, and the parameter a which indicates how far from the ideal design the electrodes are. We study the case P _φ = 0. By means of surfaces of section, we show that the phase space structure is made of three fundamental families of orbits: arch, loop and box orbits. The coexistence of these kinds of orbits depends on the parameter δ. The escape is also explained on the basis of the shape of the potential energy surface as well as of the phase space structure. Received 6 September 2001 / Received in final form 19 March 2002 Published online 28 June 2002     

Dynamics of a single ion in a perturbed Penning trap: octupolar perturbation

Imperfections in the design or implementation of Penning traps may give rise to electrostatic perturbations that introduce nonlinearities in the dynamics. In this paper we investigate, from the point of view of classical mechanics, the dynamics of a single ion trapped in a Penning trap perturbed by an octupolar perturbation. Because of the axial symmetry of the problem, the system has two degrees of freedom. Hence, this model is ideal to be managed by numerical techniques like continuation of families of periodic orbits and Poincaré surfaces of section. We find that, through the variation of the two parameters controlling the dynamics, several periodic orbits emanate from two fundamental periodic orbits. This process produces important changes (bifurcations) in the phase space structure leading to chaotic behavior.     

Penning阱中H+n团簇离子运动的分析

根据在实验中所采用的Penning离子阱的结构及电磁场分布特点,列出阱内离子运动方程并进行求解,并对Pen-ning阱内团簇离子的二种运动进行详细分析,最后对所作的研究进行了总结.     

Observing a single hydrogen-like ion in a Penning trap at T = 4 K

We describe how a single hydrogen-like ion (C⁵⁺) is prepared, cooled with the method of resistive cooling and non-destructively detected with the image-current technique in a cryogenic Penning trap at T = 4 K. The storage time for C⁵⁺-ions in the cryogenically pumped vacuum chamber is longer than six months. The experimental techniques of preparing, cooling and detecting highly-charged ions in a Penning trap are relevant for precision experiments such as g-factor measurements, mass spectroscopy and laser spectroscopy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Operation of a planar Penning trap

We demonstrate experimentally the confinement of electrons in a novel planar Penning trap. Measurement of the eigenfrequencies of the trapped electron cloud exhibits similar behaviour as in conventional 3-dimensional penning traps. The trap may be of future use in quantum computing schemes using single cold electrons.     

Motional frequencies in a planar Penning trap

A Penning trap consisting of concentric ring electrodes on a substrate and a magnetic field perpendicular to the substrate plane has been loaded with electrons. In order to demonstrate the performance of the trap we have measured the motional frequencies of the trapped electrons. Frequencies, line shape and width agree well with simulations. Miniaturization of the device is at hand which opens novel possibilities for application in quantum computing. Contribution presented at the TCP06, Vancouver Island, 2006-09-21     

Formation of fullerene dianions in a Penning trap

Fullerene dianions in the range C₇₀^2- to C₉₀^2- have been created by subjecting trapped fullerene monoanions to low energy electrons in a Penning trap. The dianion production was found to be a function of the trapping-potential depth and the time of interaction between the simultaneously stored monoanions and electrons. Under similar conditions the dianion yield depends on the size of the fullerenes with more than 10% of the trapped C₉₀^- ions forming dianions while the corresponding relative yield for C₇₀^2- was less than 0.1%. The large difference can be explained by the repulsive Coulomb barrier and the second electron affinity of the fullerenes.     

Dynamics of charged particles in a Penning trap

An automodel solution of self-consistent equations for an ellipsoidal cluster of Coulomb particles in a Penning trap is obtained.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 18–21, July, 1994.     

Adiabatic cooling of antiprotons in a Penning trap

An antiproton cloud cooled at 4.2 K in a Penning trap can be further cooled by adiabatic reduction of the trap magnetic and electric fields. It will be shown that the temperature can be reduced by two orders of magnitude. This cooling method may be useful to obtain ultra-low energy antiprotons for the measurement of their gravitational properties and the production of ultra-low energy antihydrogen atoms.