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The Fingerprints of Periodic Electric Fields on Line Shapes Emitted in Plasmas 周期电场在等离子体发射线形上的指纹图谱
Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-10-08 DOI: 10.3390/atoms11100128
Ibtissem Hannachi, Roland Stamm
Periodic electric fields are found in many kinds of plasmas and result from the presence of collective fields amplified by plasma instabilities, or they are created by external sources such as microwave generators or lasers. The spectral lines emitted by atoms or ions in a plasma exhibit a frequency profile characteristic of plasma conditions, such as the temperature and density of charged particles. The fingerprints of periodic electric fields appear clearly on the line shape for a large range of frequencies and magnitudes of the oscillating electric field. Satellite structures appear near to multiples of the oscillation frequency and redistribute the intensity of the line far from the line center. The modeling of the simultaneous effects of the plasma microfield and of a periodic electric field has been active since the seventies, but it remains difficult to be conducted accurately since the quantum emitter is submitted to several time-dependent electric fields, each with their own characteristic time. We describe here a numerical approach which couples a simulation of the motion of charged plasma particles with an integration of the emitter Schrödinger equation. Resulting hydrogen line shapes are presented for different plasmas and periodic fields encountered in laboratory and astrophysical plasmas.
周期电场存在于多种等离子体中,由等离子体不稳定性放大的集体场产生,或者由微波发生器或激光等外部源产生。等离子体中原子或离子发出的谱线表现出等离子体条件的频率特征,如带电粒子的温度和密度。周期电场的指纹在较大的振荡电场频率和振幅范围内清晰地呈现在线形上。卫星结构出现在振荡频率的几倍附近,并在远离线中心的地方重新分布线的强度。等离子体微场和周期电场同步效应的建模自70年代以来一直很活跃,但由于量子发射极受到几个时间相关的电场的影响,每个电场都有自己的特征时间,因此很难准确地进行建模。我们在这里描述了一种数值方法,该方法将带电等离子体粒子的运动模拟与发射器Schrödinger方程的积分耦合在一起。在实验室和天体物理等离子体中遇到的不同等离子体和周期场的氢线形状。
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引用次数: 0
Status of CHIP-TRAP: The Central Michigan University High-Precision Penning Trap CHIP-TRAP的现状:中密歇根大学高精度Penning Trap
Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-10-07 DOI: 10.3390/atoms11100127
Nadeesha Gamage, Madhawa Horana, Rachel Sandler, Ramesh Bhandari, Matthew Redshaw
Precise and accurate atomic mass data provide crucial information for applications in a wide range of fields in physics and beyond, including astrophysics, nuclear structure, particle and neutrino physics, fundamental symmetries, chemistry, and metrology. The most precise atomic mass measurements are performed on charged particles confined in a Penning trap. Here, we describe the development, status, and outlook of CHIP-TRAP: the Central Michigan University high-precision Penning trap. CHIP-TRAP aims to perform ultra-high precision (∼1 part in 1011 fractional precision) mass measurements on stable and long-lived isotopes produced with external ion sources and transported to the Penning traps. Along the way, ions of a particular m/q are selected with a multi-reflection time-of-flight mass separator (MR-TOF-MS), with further filtering performed in a cylindrical capture trap before the ions are transported to a pair of hyperbolic measurement traps. In this paper, we report on the design and status of CHIP-TRAP and present results from the commissioning of the ion sources, MR-TOF-MS, and capture trap. We also provide an outlook on the continued development and commissioning of CHIP-TRAP.
精确和准确的原子质量数据为物理学和其他领域的广泛应用提供了关键信息,包括天体物理学、核结构、粒子和中微子物理学、基本对称性、化学和计量学。最精确的原子质量测量是对限制在潘宁阱中的带电粒子进行的。在这里,我们描述CHIP-TRAP的发展,现状和前景:中密歇根大学高精度Penning trap。CHIP-TRAP旨在对由外部离子源产生并输送到Penning陷阱的稳定和长寿命同位素进行超高精度(约1 / 1011分数精度)的质量测量。在此过程中,使用多反射飞行时间质量分离器(MR-TOF-MS)选择特定m/q的离子,在离子被输送到一对双曲线测量陷阱之前,在圆柱形捕获陷阱中进行进一步过滤。在本文中,我们报告了CHIP-TRAP的设计和状态,并介绍了离子源,MR-TOF-MS和捕获陷阱的调试结果。我们还对CHIP-TRAP的持续开发和调试进行了展望。
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引用次数: 0
Single Ionization of Helium by Protons of Various Energies in the Parabolic Quasi-Sturmians Approach 不同能量的质子在抛物线准图尔米斯方法中的氦的单电离
Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-09-28 DOI: 10.3390/atoms11100124
Alexander S. Zaytsev, Darya S. Zaytseva, Sergey A. Zaytsev, Lorenzo U. Ancarani, Ochbadrakh Chuluunbaatar, Konstantin A. Kouzakov, Yury V. Popov
The parabolic quasi-Sturmian approach, recently introduced for the calculation of ion–atom ionizing collisions, is adapted and applied here to the single ionization of helium induced by an intermediate-energy proton impact. Within the method, the ionization amplitude is represented as the sum of the products of the basis amplitudes associated with the asymptotic behavior of the continuum states of the two noninteracting hydrogenic subsystems (e−,He+) and (p+,He+). The p−e interaction is treated as a perturbation in the Lippmann–Schwinger-type (LS) equation for the three-body system (e−,He+,p+). This LS equation is solved numerically using separable expansions for the proton–electron potential. We examine the convergence behavior of the transition amplitude expansion as the number of terms in the representation of the p−e interaction is increased and find that, for some kinematic regimes, the convergence is poor. This difficulty, which is absent for a higher proton energy impact, is solved by varying the momentum of the auxiliary proton plane wave introduced into the basis function. Fully differential cross-sections are calculated and compared with experimental data for 75 keV protons and the results obtained with the 3C model.
最近引入的计算离子-原子电离碰撞的抛物线准sturmian方法,在这里被改编并应用于由中能量质子撞击引起的氦的单电离。在该方法中,电离振幅表示为与两个非相互作用氢子系统(e−,He+)和(p+,He+)的连续态渐近行为相关的基振幅的乘积之和。在三体系统(e−,He+,p+)的lippmann - schwinger型(LS)方程中,p−e相互作用被视为扰动。利用质子-电子势的可分离展开对LS方程进行了数值求解。我们研究了随着p−e相互作用的表示中项数的增加,过渡幅度扩展的收敛行为,并发现,对于某些运动区域,收敛性很差。这一困难,这是不存在的较高的质子能量的冲击,是通过改变辅助质子平面波的动量引入基函数解决。计算了75 keV质子的全微分截面,并与实验数据和3C模型的结果进行了比较。
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引用次数: 0
Quadrupole Effects in the Photoionisation of Sodium 3s in the Vicinity of the Dipole Cooper Minimum 偶极子库伯极小值附近钠3s光离的四极效应
Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-09-28 DOI: 10.3390/atoms11100125
Nishita M. Hosea, Jobin Jose, Hari R. Varma, Pranawa C. Deshmukh, Steven T. Manson
A procedure to obtain relativistic expressions for photoionisation angular distribution parameters using the helicity formulation is discussed for open-shell atoms. Electric dipole and quadrupole transition matrix elements were considered in the present work, to study the photoionisation dynamics of the 3s electron of the sodium atom in the vicinity of the dipole Cooper minimum. We studied dipole–quadrupole interference effects on the photoelectron angular distribution in the region of the dipole Cooper minimum. Interference with quadrupole transitions was found to alter the photoelectron angular distribution, even at rather low photon energies. The initial ground and final ionised state discrete wavefunctions of the atom were obtained in the present work using GRASP, and we employed RATIP with discrete wavefunctions, to construct continuum wavefunctions and to calculate transition amplitudes, total cross-sections and angular distribution asymmetry parameters.
讨论了开壳原子的光离角分布参数的螺旋公式的相对论表达式。本文考虑电偶极子和四极子跃迁矩阵元素,研究了钠原子在偶极子库柏最小值附近3s电子的光离动力学。研究了偶极子-四极子干涉对偶极子库柏极小值区光电子角分布的影响。发现四极跃迁的干扰会改变光电子的角分布,即使在相当低的光子能量下也是如此。本文利用GRASP获得了原子的初始基态和最终电离态离散波函数,并利用离散波函数的RATIP构造了连续波函数,计算了跃迁振幅、总截面和角分布不对称参数。
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引用次数: 0
Applications of Machine Learning and Neural Networks for FT-ICR Mass Measurements with SIPT 机器学习和神经网络在SIPT FT-ICR质量测量中的应用
Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-09-28 DOI: 10.3390/atoms11100126
Scott E. Campbell, Georg Bollen, Alec Hamaker, Walter Kretzer, Ryan Ringle, Stefan Schwarz
The single-ion Penning trap (SIPT) at the Low-Energy Beam Ion Trapping Facility has been developed to perform precision Penning trap mass measurements of single ions, ideal for the study of exotic nuclei available only at low rates at the Facility for Rare Isotope Beams (FRIB). Single-ion signals are very weak—especially if the ion is singly charged—and the few meaningful ion signals must be disentangled from an often larger noise background. A useful approach for simulating Fourier transform ion cyclotron resonance signals is outlined and shown to be equivalent to the established yet computationally intense method. Applications of supervised machine learning algorithms for classifying background signals are discussed, and their accuracies are shown to be ≈65% for the weakest signals of interest to SIPT. Additionally, a deep neural network capable of accurately predicting important characteristics of the ions observed by their image charge signal is discussed. Signal classification on an experimental noise dataset was shown to have a false-positive classification rate of 10.5%, and 3.5% following additional filtering. The application of the deep neural network to an experimental 85Rb+ dataset is presented, suggesting that SIPT is sensitive to single-ion signals. Lastly, the implications for future experiments are discussed.
低能束离子捕获装置的单离子彭宁阱(SIPT)用于对单离子进行精确的彭宁阱质量测量,非常适合研究稀有同位素束装置(FRIB)中只有低速率才能获得的外来核。单离子信号非常微弱——尤其是当离子是单电荷的时候——而且少数有意义的离子信号必须从通常较大的噪声背景中分离出来。本文提出了一种有效的模拟傅里叶变换离子回旋共振信号的方法,并证明该方法与已建立的计算强度较高的方法等效。讨论了有监督机器学习算法在背景信号分类中的应用,对于SIPT感兴趣的最弱信号,其精度显示为≈65%。此外,还讨论了一种能够准确预测离子图像电荷信号所观察到的重要特性的深度神经网络。在实验噪声数据集上的信号分类显示假阳性分类率为10.5%,在额外滤波后为3.5%。将深度神经网络应用于85Rb+实验数据集,表明SIPT对单离子信号敏感。最后,讨论了对未来实验的启示。
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引用次数: 0
The Double-Nozzle Technique Equipped with RF-Only Funnel and RF-Buncher for the Ion Beam Extraction into Vacuum 配备rf漏斗和rf聚束器的双喷嘴技术用于离子束真空抽提
Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-09-22 DOI: 10.3390/atoms11100123
Victor Varentsov
This study is a further development of our “Proposal of a new double-nozzle technique for in-gas-jet laser resonance ionization spectroscopy” paper published in the journal Atoms earlier this year. Here, we propose equipping the double-nozzle technique with the RF-only funnel and RF-buncher placed in a gas-jet chamber at a 70 mm distance downstream of the double-nozzle exit. It allows for highly effective extraction into vacuum heavy ion beams, produced in two-steps laser resonance ionization in the argon supersonic jet. We explored the operation of this new full version of the double-nozzle technique through detailed gas dynamic and Monte Carlo trajectory simulations, with the results presented and discussed. In particular, our calculations showed that more than 80% of all nobelium-254 neutral atoms, extracted by argon flow from the gas-stopping cell, can then be extracted into vacuum in a form of pulsed ion beam having low transverse and longitudinal emittance.
这项研究是我们在今年早些时候发表在《原子》杂志上的论文《关于一种新的气体喷射激光共振电离光谱双喷嘴技术的建议》的进一步发展。在这里,我们建议在双喷嘴出口下游70毫米距离处的气体喷射室中配备仅rf漏斗和rf集束器的双喷嘴技术。它允许高度有效地提取到真空重离子束,在氩气超音速射流中产生两步激光共振电离。我们通过详细的气体动力学和蒙特卡罗轨迹模拟,探索了这种新的完整版本的双喷嘴技术的操作,并给出了结果并进行了讨论。特别地,我们的计算表明,超过80%的所有的nobel254中性原子,通过氩气流从气停池中提取,然后可以以脉冲离子束的形式提取到真空中,具有低的横向和纵向发射度。
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引用次数: 0
Stark Broadening of Lyman-α in the Presence of a Strong Magnetic Field 强磁场作用下Lyman-α的Stark展宽
Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-09-15 DOI: 10.3390/atoms11090120
Evgeny Stambulchik
Stark broadening of Lyman-α of a hydrogen-like atom in the presence of a strong magnetic field is analyzed. The shape of the central (π) component of the Lorentz–Zeeman triplet is expressed analytically, taking into account the plasma coupling and microfield dynamic effects. It is shown that in a sufficiently strong magnetic field, the broadening of this component, contrary to the broadening of the lateral (σ) ones, is independent of the magnetic field and, therefore, can be used for the plasma density diagnostics. Comparison with computer simulations at conditions typical for tokamak divertors and white dwarf atmospheres shows a very good agreement.
分析了类氢原子Lyman-α在强磁场作用下的Stark展宽。考虑等离子体耦合和微场动力学效应,用解析的方法表达了洛伦兹-塞曼三重态中心(π)分量的形状。结果表明,在足够强的磁场中,该分量的展宽与横向分量(σ)的展宽相反,与磁场无关,因此可用于等离子体密度诊断。与典型托卡马克引流器和白矮星大气条件下的计算机模拟结果比较,结果吻合得很好。
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引用次数: 0
Electronic Structure, Spectroscopy, Cold Ion–Atom Elastic Collision Properties, and Photoassociation Formation Prediction of the (MgCs)+ Molecular Ion (MgCs)+分子离子的电子结构、光谱学、冷离子-原子弹性碰撞特性和光缔合形成预测
Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-09-15 DOI: 10.3390/atoms11090121
Mohamed Farjallah, Dibyendu Sardar, Bimalendu Deb, Hamid Berriche
In this paper, we extensively study the electronic structure, interactions, and dynamics of the (MgCs)+ molecular ion. The exchanges between the alkaline atom and the low-energy cationic alkaline earths, which are important in the field of cold and ultracold quantum chemistry, are studied. We use an ab initio approach based on the formalism of non-empirical pseudo-potential for Mg2+ and Cs+ cores, large Gaussian basis sets, and full-valence configuration interaction. In this context, the (MgCs)+ cation is treated as an effective two-electron system. Adiabatic potential energy curves and their spectroscopic constants for the ground and the first 20 excited states of 1,3Σ+ symmetries are determined. Furthermore, we identify the avoided crossings between the electronic states of 1,3Σ+ symmetries. These crossings are related to the charge transfer process between the two ionic limits, Mg/Cs+ and Mg+/Cs. Therefore, vibrational-level spacings and the transition and permanent dipole moments are presented and analyzed. Using the produced potential energy data, the ground-state scattering wave functions and elastic cross-sections are calculated for a wide range of energies. In addition, we predict the formation of a translationally and rotationally cold molecular ion (MgCs)+ in the ground-state electronic potential energy through a stimulated Raman-type process aided by ion–atom cold collision. In the low-energy limit (<1 mK), elastic scattering cross-sections exhibit Wigner law threshold behavior, while in the high-energy limit, the cross-sections act as a function of energy E go as E−1/3. A qualitative discussion about the possibilities of forming cold (MgCs)+ molecular ions by photoassociative spectroscopy is presented.
在本文中,我们广泛地研究了(MgCs)+分子离子的电子结构、相互作用和动力学。研究了低温和超冷量子化学中具有重要意义的碱性原子与低能阳离子碱土之间的交换。我们使用了一种基于Mg2+和Cs+核、大高斯基集和全价态相互作用的非经验伪势形式化的从头算方法。在这种情况下,(MgCs)+阳离子被视为一个有效的双电子系统。确定了1,3Σ+对称的基态和前20个激发态的绝热势能曲线及其光谱常数。此外,我们确定了1,3Σ+对称电子态之间的避免交叉。这些交叉与两个离子极限Mg/Cs+和Mg+/Cs之间的电荷转移过程有关。因此,给出并分析了振动级间距、跃迁矩和永久偶极矩。利用生成的势能数据,计算了大范围能量下的基态散射波函数和弹性截面。此外,我们预测了在离子-原子冷碰撞的辅助下,通过受激拉曼过程在基态电子势能下形成平移和旋转冷分子离子(MgCs)+。在低能极限(<1 mK),弹性散射截面表现为Wigner定律阈值行为,而在高能极限,弹性散射截面表现为能量E go的函数,为E−1/3。本文对光结合光谱法形成冷(MgCs)+分子离子的可能性进行了定性讨论。
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引用次数: 0
Ionization of Hydrogen Atom by Proton Impact—How Accurate Is the Ionization Cross Section? 质子撞击使氢原子电离——电离截面有多精确?
Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-09-15 DOI: 10.3390/atoms11090122
Károly Tőkési, Saleh Alassaf
For the control of fusion reactors, we need to accurately know all the possible reactions and collisional cross sections. Although large-scale trials have been performed over the last decades to obtain this data, many basic atomic and molecular cross section data are missing and the accuracy of the available cross sections need to be checked. Using the available measured cross sections and theoretical predictions of hydrogen atom ionization by proton impact, critical analysis of the data is presented. Moreover, we also present our recent classical results based on the standard classical trajectory Monte Carlo (CTMC) and quasi-classical trajectory Monte Carlo (C-QCTMC) models. According to our model calculations and comparison with the experimental data, recom-mended cross sections for ionization of hydrogen were presented in a wide range of pro-jectile impact energies. We found that, while in the low energy region, the experimental cross sections are very close to the C-QCTMC results, at higher energies, they are close to the results of our standard CTMC results.
为了控制聚变反应堆,我们需要准确地知道所有可能的反应和碰撞截面。虽然在过去的几十年里进行了大规模的试验来获得这些数据,但许多基本的原子和分子截面数据缺失,需要检查可用截面的准确性。利用现有的测量截面和质子撞击使氢原子电离的理论预测,对数据进行了批判性分析。此外,我们还介绍了基于标准经典轨迹蒙特卡罗(CTMC)和准经典轨迹蒙特卡罗(C-QCTMC)模型的最新经典结果。根据模型计算并与实验数据对比,给出了在较宽的弹丸冲击能量范围内氢电离的推荐截面。我们发现,在低能区,实验截面与C-QCTMC的结果非常接近,在高能区,实验截面与我们的标准CTMC的结果非常接近。
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引用次数: 0
g Factor of Few-Electron Highly Charged Ions 少电子高电荷离子的g因子
Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-09-08 DOI: 10.3390/atoms11090119
Dmitry A. Glazov, Dmitrii V. Zinenko, Valentin A. Agababaev, Artyom D. Moshkin, Elizaveta V. Tryapitsyna, Anna M. Volchkova, Andrey V. Volotka
The current status of the theoretical investigation of the bound-electron g factor in lithium-like and boron-like highly charged ions is reported. Some tension between the several theoretical values and measurements is discussed. Then, prospects for future investigations are briefly reviewed.
本文报道了类锂和类硼高电荷离子中束缚电子g因子的理论研究现状。讨论了几个理论值与测量值之间的矛盾。并对今后的研究进行了展望。
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引用次数: 0
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