Monte Carlo simulation of ion motion in drift tubes

Lin, Shu; Bardsley, J. N.

doi:10.1063/1.433988

Cited by 219 publications

(81 citation statements)

References 32 publications

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“…The proposed procedure, while somewhat more complex than the basic MC procedure of [31] is not significantly more demanding in terms of computation time. The only difference is the sampling of the background velocities using the distribution (18).…”

Section: Discussionmentioning

confidence: 99%

“…In general the needs for data for modeling of plasmas including the low energy limit [57,58,75,76] show that this procedure should be implemented in all the MC codes when accurate data are required including the ability to represent spatial and temporal dependencies of the field. It is important to note that procedure in [31] or cold gas approximation become sufficiently accurate at energies that are several times larger than the thermal energy, in the case of ions in their parent gas. The reason why the problem with the sampling was not found some years ago was due to the fact that only a few studies were made that focused on very low energies and also because statistics of simulations was too poor to notice the effects.…”

Section: Discussionmentioning

confidence: 99%

“…One of the first papers that addressed the question of thermal effects of the background gas was the one of Lin and Bardsley [31]. They used an approximate treatment and sampled the velocities of the host gas directly from the gas distribution function when an ion collided with a host particle.…”

Section: A Boltzmann Equation and The Distribution Functionmentioning

confidence: 99%

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A Monte Carlo simulation of ion transport at finite temperatures

Ristivojević

Petrović

2012

Plasma Sources Sci. Technol.

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We have developed a Monte Carlo simulation for ion transport in hot background gases, which is an alternative way of solving the corresponding Boltzmann equation that determines the distribution function of ions. We consider the limit of low ion densities when the distribution function of the background gas remains unchanged due to collision with ions. A special attention has been paid to properly treat the thermal motion of the host gas particles and their influence on ions, which is very important at low electric fields, when the mean ion energy is comparable to the thermal energy of the host gas. We found the conditional probability distribution of gas velocities that correspond to an ion of specific velocity which collides with a gas particle. Also, we have derived exact analytical formulas for piecewise calculation of the collision frequency integrals. We address the cases when the background gas is monocomponent and when it is a mixture of different gases. The developed techniques described here are required for Monte Carlo simulations of ion transport and for hybrid models of non-equilibrium plasmas. The range of energies where it is necessary to apply the technique has been defined. The results we obtained are in excellent agreement with the existing ones obtained by complementary methods. Having verified our algorithm, we were able to produce calculations for Ar + ions in Ar and propose them as a new benchmark for thermal effects. The developed method is widely applicable for solving the Boltzmann equation that appears in many different contexts in physics.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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A Monte Carlo simulation of ion transport at finite temperatures

Ristivojević

Petrović

2012

Plasma Sources Sci. Technol.

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“…Such fields typically can be calculated for a variety of device geometries and applied potentials, following which numerical integration of Newton's equations enables simulation of the complicated ion trajectory. The use of various mathematical methods, ranging from constant damping terms to Monte Carlo methods [29,[37][38][39], allows collisional processes to be approximated in such simulations. The weakness of such trajectory simulation approaches is that investigation of the collective behavior of an ensemble of ions requires trajectory simulations to be performed for multiple ions, either individually or simultaneously.…”

mentioning

confidence: 99%

“…Higher-order moment methods, developed from twotemperature [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] and multi-temperature [46,47] approaches to solving the Boltzmann kinetic equation, provide a series of successive approximations for further improving the accuracy. Momentum-transfer and higher-order moment theories have been developed recently for situations where the electric and magnetic fields vary with position as well as with time [48].…”

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confidence: 99%

Prediction of collective characteristics for ion ensembles in quadrupole ion traps without trajectory simulations

Goeringer

Viehland

Danailov

2006

J. Am. Soc. Mass Spectrom.

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Fundamental aspects are presented of a two-temperature moment theory for quadrupole ion traps developed via transformation of the Boltzmann equation. Solutions of the moment equations correspond to changes in the ensemble average for any function of ion velocity, because the Boltzmann equation reflects changes to an ion distribution as a whole. The function of primary interest in this paper is the ion effective temperature and its behavior during ion storage and resonance excitation. Calculations suggest that increases in ion effective temperature during resonance excitation are due primarily to power absorption from the main RF trapping field rather than from the dipolar excitation signal. The dipolar excitation signal apparently serves mainly to move ions into regions of the ion trap where the RF electric field, and thus ion RF heating, is greater than near the trap center. Both ideal and non-ideal ion trap configurations are accounted for in the moment equations by incorporating parameterized variables ã and q, which are modified versions of the commonly used forms for the DC and AC ring voltages, and b and d, which are new forms that account for the voltages applied to the endcaps. Besides extending the applicability of the moment equations to non-ideal quadrupole ion traps, the modified versions of the parameterized variables can have additional utility. T oday, a large number of analytical mass spectrometers depend exclusively upon electric fields for ion transport, manipulation, and mass analysis. The fields employed may be static (e.g., time-offlight) [1], dynamic (e.g., RF quadrupole [2][3][4][5]), or a combination of the two [6 -8]. Improvements in performance of RF devices have been realized by changes in the physical configuration and applied potentials [9 -12], which produce electric fields of increased complexity (e.g., hexapole, octapole, etc.). Furthermore, ion motion and physicochemical phenomena in such RF devices are influenced by the introduction of a buffer gas at substantial pressure. The high number of ionneutral collisions resulting from extended ion residence times and elevated buffer gas number density can prove beneficial for ion cooling and focusing [13,14]. In contrast, the average kinetic energy of the ions also can be increased significantly above the thermal energy of the neutrals via acceleration in an electric field. The most widely used approach for ion acceleration in electrodynamic ion traps, termed resonance excitation, uses a relatively low-amplitude AC signal at the fundamental frequency of ion axial oscillations applied to the endcaps [15]. An important application of that process in RF multipole devices is collisional activation (CA) [15], in which a portion of the ion-neutral relative (i.e., center-of-mass) kinetic energy is transferred into internal energy of the ions. In such instances, although the kinetic energy associated with any individual collision is generally small, the cumulative effect of multiple collisions enables the collision-induced dissociation (CID) o...

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Evaluation of computing capabilities of a hierarchy of mini‐to‐supercomputers: Applications to ion microscopic analysis

Ling

Bernardo

Morrison

1988

Journal of Chemometrics

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There has been a steadily increasing demand for more computational power in surface and interface analysis. This paper reports attempts to meet these demands through the use of different computing systems, ranging from minicomputer to supercomputer. Representative laboratory data processing programs for ion microscopic analysis are used to evaluate the performance of each system. The bottlenecks and other problems involved in running analytical programs on faster machines are identified and discussed. Results indicate that in order to attain the optimal cost-performance ratio, programs must be tailored to specific forms required by the computing system. Algorithms must be formulated to exploit available vector and parallel processing capabilities. KEY WORDSComputing system performance evaluation Ion microscopic analysis Digital image processing Monte Carlo simulations Supercomputer

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Monte Carlo simulation of ion motion in drift tubes

Abstract: Monte Carlo simulation of Brownian motion with viscous dragAm.

Cited by 219 publications

References 32 publications

A Monte Carlo simulation of ion transport at finite temperatures

A Monte Carlo simulation of ion transport at finite temperatures

Prediction of collective characteristics for ion ensembles in quadrupole ion traps without trajectory simulations

Evaluation of computing capabilities of a hierarchy of mini‐to‐supercomputers: Applications to ion microscopic analysis

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