Trajectory Simulation Program Research Articles

Integrated Aerodynamic and Trajectory Studies of a Long-Range Morphing Missile

A morphing missile aims to get optimal flight performances at different flight conditions by a variable aerodynamic shape according to the requirements of multiple missions. For a long-range missile with morphing wings, an integrated method with a morphing geometry, an aerodynamic analysis, and a trajectory simulation program was studied for a wider range. The morphing configuration was designed to improve aerodynamic properties by variable-sweep wings. Those aerodynamic features were then divided into three parts, including both flight Mach numbers and lift-to-drag ratios through detailed aerodynamic analyses. Based on such classifications, we first proposed the combination rules to morph by combining the maximal lift-to-drag ratio with the minimal drag or the maximum pitching moment gradient coefficient. The trajectory simulation program used within the gliding and morphing strategies was then launched. Our results demonstrated both strategies were beneficial for extending the attack ranges of long-range missiles subject to the constraints of stabilities and variable flight conditions. The gliding strategy provided 119.5–45.6% increases in range over the baseline geometry; the morphing scheme also succeeded in increasing the range over the deployment of the gliding strategy by an additional 20.7–46.8%.

The Resonant Excitation Process in Commercial Quadrupole Ion Traps Revisited.

The collision-induced resonant excitation process in real quadrupole ion traps is revisited theoretically and experimentally by explicitly including in the discussion the influence of higher order potential impurities. This includes mainly the dependence of the secular oscillation frequency fion on the ion's oscillation amplitude zmax. Due to frequency calibration, commercial ion traps use excitation frequencies fexc that are higher than the theoretical secular oscillation frequency fion. This may lead to switching in frequency order between fexc and fion that can allow ions to stay longer in on-resonance. It is also found that there is a most efficient but also a harshest excitation frequency, which are not identical. These phenomena are explained and described with a simple harmonic oscillator model and precise numerical calculations, using the trajectory simulation program ITSIM 5.0. Experimental MS2 have been performed with the thermometer ion leucine-enkephalin, which are then in line with expectations from the trajectory calculations. The important difference to the existing literature is that, here, overexcitation is characterized by the observed a4/b4 fragment-ion ratio, while the fragmentation efficiency was kept constant. By slightly increasing the excitation frequency one can obtain drastically different effective collisional temperatures. This knowledge gives even commercial ion traps, without instrument adjustments, the possibility of producing energetically versatile fragment ion spectra. It is also shown that the damped driven harmonic oscillator cannot be used as a simplified model of the motion during the resonant excitation process in real ion traps.

Conceptual designing of a slow positron beam system using Simion simulation program

The slow positron beam system is an important device in the study of positron physics and techniques, especially in materials research. This paper presents obtained results in studying and applying a charged particles trajectory simulation program – Simion for building feasible design models for the system. The built models with different designs based on reference designs of some typical systems include a straight-shaped model, a 500 bent-shaped model and a 900 bent-shaped model. Some positron beam trajectory calculation tests have been performed for comparison between the models. From the tests, the 500 bent-shaped model has been proposed as a conceptual design for building a real slow positron beam system in the future in Vietnam.

GPU Assisted Simulation Study of Ion-Ion Reactions within Quadrupole Ion Traps.

In this study, a gas-phase ion-ion reaction model was developed, and it was integrated into an ion trajectory simulation program. GPU parallel computation techniques were also applied to accelerate the simulation process. With this simulation tool, the dependence of ion-ion reaction rate within 3D quadrupole ion traps on both ion trap operation parameters and the characteristics of reaction pair were investigated. It was found that the m/z values and charge states of ions have significant influences on the reaction rate. Moreover, higher ion-ion reaction rate was achieved under higher trapping voltages and higher buffer gas pressures. Furthermore, secondary reaction and/or neutralization of ETD fragment ions were observed from simulation. The reaction and/or neutralization rate depends on the charge state and m/z of each fragment ion.

Prefocusing inside a linear ion beam guide—A SIMION study

A set of 14 stacked ring electrodes was studied by the SIMION ion trajectory simulation program under a pressure of 1Pa with different applied RF frequencies and RF voltage amplitudes when a classical DC gradient of 38V/cm is applied. Ion–neutral collision effects were considered by adopting a successful and integrated hard sphere, elastic, ion–neutral collision user program provided by SIMION. Mass dependent ion transmission efficiencies could be obtained. In the classical operation mode of the ion beam guide, a RF frequency of 2MHz was crucial to obtain very good ion transmission efficiency along a broad mass range. Lower RF frequencies (<1.5MHz) limited the good transmission efficiencies only to high masses with m/z>500amu. SIMION can reproduce expected efficiency curves which show that low m/z ions below 150amu represent a challenge for such linear ion beam devices even when high RF driving frequency of 2MHz is applied. The simulations also show that a DC gradient of at least 30V/cm is crucial to maintain good transmission efficiencies which are in agreement with previously published results. A new operation mode for running the same device is introduced for earlier ion focusing in between the second and fifth ring electrodes, prior to slight beam divergence after the focus point. This required a significant change of the applied DC voltages to alter the shape of the DC gradient curve along the central z axis. The newly identified operation mode allows enhancing the mass dependent ion transmission efficiency in a wide m/z range between 80 and 1000amu when an RF frequency of 2MHz is applied to the first ten ring electrodes.

Construction of a Newly Designed Small-Size Mass Spectrometer for Helium Isotope Analysis: Toward the Continuous Monitoring Of 3He/4He Ratios In Natural Fluids

The construction of a small-size, magnetic sector, single focusing mass spectrometer (He-MS) for the continuous, on-site monitoring of He isotope ratios ((3)He/(4)He) is described. The instrument is capable of measuring (4)He/(20)Ne ratios dissolved in several different types of natural fluids of geochemical interest, such as groundwater and gas from hot springs, volcanoes and gas well fields. The ion optics of He-MS was designed using an ion trajectory simulation program "TRIO," which permits the simultaneous measurement of (3)He and (4)He with a double collector system under a mass resolution power (M/ΔM) of >700. The presently attained specifications of He-MS are; (1) a mass resolving power of ca. 430, sufficient to separate (3)He(+) from interfering ions, HD(+) and H3 (+), (2) ultra-high vacuum conditions down to 3×10(-8) Pa, and (3) a sufficiently high sensitivity to permit amounts of (3)He to be detected at levels as small as 10(-13) cm(3) STP (3×10(6) atoms). Long term stability for (3)He/(4)He analysis was examined by measuring the (3)He/(4)He standard gas (HESJ) and atmospheric He, resulting in ∼3% reproducibility and ≤5% experimental error for various amounts of atmospheric He from 0.3 to 2.3×10(-6) cm(3) STP introduced into the instrument. A dynamic range of measurable (3)He/(4)He ratios with He-MS is greater than 10(3) which was determined by measuring various types of natural fluid samples from continental gas (with a low (3)He/(4)He ratio down to 2×10(-8)) to volcanic gas (with a high (3)He/(4)He ratio up to 3×10(-5)). The accuracy and precision of (3)He/(4)He and (4)He/(20)Ne ratios were evaluated by comparing the values with those measured using well established noble gas mass spectrometers (modified VG5400/MS-III and -IV) in our laboratory, and were found to be in good agreement within analytical errors. Usefulness of the selective extraction of He from water/gas using a high permeability of He through a silica glass wall at high temperature (700°C) is demonstrated.

Sports ball aerodynamics: A numerical study of the erratic motion of soccer balls

The application of the commercial CFD code, FLUENT, to sports ball aerodynamics was assessed and a validated 3D analysis technique was established for balls that have been scanned with a 3D laser scanner or drawn in CAD. The technique was used to examine the effects of surface geometry on the aerodynamic behaviour of soccer balls by comparing the flow around different balls and predicting the aerodynamic force coefficients. The validation process included performing CFD studies on 3D smooth spheres and various soccer balls, and comparing the results to wind tunnel tests and flow visualisation. The CFD technique used a surface wrapping meshing method and the Reynolds Averaged Navier–Stokes approach with the realizable k-ε turbulence model, which was found to be able to predict the drag, lift and side force coefficients ( C D , C L and C S ) reliably, to compare the wake behaviour, and to give good pressure distributions near the stagnation point. The main limitations of the technique with the available computational resources were its inability to accurately predict boundary layer transition or growth, but despite this, several conclusions could be drawn regarding soccer ball aerodynamics. C D was not significantly different between balls. C L and C S were found to be significantly affected by the orientation of the ball relative to its direction of travel, meaning that balls kicked with low amounts of spin could experience quasi-steady lift and side forces and move erratically from side-to-side or up and down through the air. For different balls, C D , C L and C S were predicted and their variation with orientation entered into a modified trajectory simulation program. The erratic nature of this type of kick was found to vary with details of the surface geometry including seam size, panel symmetry, number, frequency and pattern, as well as the velocity and spin applied to the ball by the player. Exploitation of this phenomenon by players and ball designers could have a significant impact on the game.

マルチターン飛行時間型質量分析計のイオン像のシミュレーション

The ion beam profiles of the multi-turn time-of-flight mass spectrometers “MULTUM” and “MULTUM II” were simulated using the ion trajectory simulation program “TRIO 2.0.” These ion optical systems satisfy the “perfect focusing” conditions and are suitable for an imaging mass spectrometer in stigmatic mode. From the simulation, it was clear that the higher order aberration of MULTUM II is smaller than that of MULTUM. A smaller initial lateral angular deviation makes aberration after circulation smaller in both the ion optical systems. In the ion optical system MULTUM II, the ion images should be measured at even numbered cycles, because the second-order coefficient (x¦xx) will be cancelled after every two cycles.

Ion Trajectory Simulation for Electrode Configurations with Arbitrary Geometries

A multi-particle ion trajectory simulation program ITSIM 6.0 is described, which is capable of ion trajectory simulations for electrode configurations with arbitrary geometries. The electrode structures are input from a 3D drawing program AutoCAD and the electric field is calculated using a 3D field solver COMSOL. The program CreatePot acts as interface between the field solver and ITSIM 6.0. It converts the calculated electric field into a field array file readable by ITSIM 6.0 and ion trajectories are calculated by solving Newton's equation using Runge-Kutta integration methods. The accuracy of the field calculation is discussed for the ideal quadrupole ion trap in terms of applied mesh density. Electric fields of several different types of devices with 3D geometry are simulated, including ion transport through an ion optical system as a function of pressure. Ion spatial distributions, including the storage of positively charged ions only and simultaneous storage of positively/negatively charged ions in commercial linear ion traps with various geometries, are investigated using different trapping modes. Inelastic collisions and collision induced dissociation modeled using RRKM theory are studied, with emphasis on the fragmentation of n-butylbenzene inside an ideal quadrupole ion trap. The mass spectrum of 1,3-dichlorobenzene is simulated for the rectilinear ion trap device and good agreement is observed between the simulated and the experimental mass spectra. Collisional cooling using helium at different pressures is found to affect mass resolution in the rectilinear ion trap.

Ion trajectory simulations of axial ac dipolar excitation in the Orbitrap

The newly developed version of the multi-particle ion trajectory simulation program, ITSIM 6.0, was applied to simulate ac dipolar excitation of ion axial motion in the Orbitrap. The Orbitrap inner and outer electrodes were generated in AutoCAD, a 3D drawing program. The electrode geometry was imported into the 3D field solver COMSOL; the field array was then imported into ITSIM 6.0. Ion trajectories were calculated by solving Newton's equations using Runge–Kutta integration methods. Compared to the analytical solution, calculated radial components of the field at the device's “equator” ( z = 0) were within 0.5% and calculated axial components midway between the inner and outer electrodes were within 0.2%. The experiments simulated here involved the control of axial motion of ions in the Orbitrap by the application of dipolar ac signals to the split outer electrodes, as described in a recently published paper from this laboratory [Hu et al., J. Phys. Chem. A 110 (2006) 2682]. In these experiments, ac signal was applied at the axial resonant frequency of a selected ion. Axial excitation and eventual ion ejection resulted when the ac was in phase with, i.e., had 0° phase relative to ion axial motion. De-excitation of ion axial motion until the ions were at z = 0 and at rest with respect to the z-axis resulted if the applied ac was out of phase with ion motion, with re-excitation of ion axial motion occurring if the dipolar ac was continued beyond this point. Both de-excitation and re-excitation could be achieved mass-selectively and depended on the amplitude and duration (number of cycles) of the applied ac. The effects of ac amplitude, frequency, phase relative to ion motion, and bandwidth of applied waveform were simulated. All simulation results were compared directly with the experimental data and good agreement was observed. Such ion motion control experiments and their simulation provide the possibility to improve Orbitrap performance and to develop tandem mass spectrometry (MS/MS) capabilities inside the Orbitrap.

Modeling and simulation of torpedo acoustic homing trajectory with multiple targets

The characteristics of a torpedo's acoustic homing trajectory with multiple targets were studied. The differential equations of torpedo motion were presented based on hydrodynamics. The Fourth order Runge-Kutta method was used to solve these equations. Derived from sonar equations and Snell’s law, a simple virtual underwater acoustic environment was established for simulating the torpedo homing process. The Newton iteration method was used to calculate homing range and ray tracing was approximated by piecewise line, which takes into consideration distortions cause by temperature, pressure, and salinity in a given sea area. The influence of some acoustic warfare equipment disturb the torpedo homing process in certain circumstances, including decoys and jammers, was alsotaken into account in simulations. Relative target identification logic and homing control laws were presented. Equal consideration during research was given to the requirements of real-timeactivity as well as accuracy. Finally, a practical torpedo homing trajectory simulation program was developed and applied to certain projects.

Design aspects of launch vehicle sizing including air-breathing propulsion

The overall sizing of launch vehicles is of interest, especially when air-breathing is also included. The sizing of a launch vehicle is dictated by the State of Art technologies present and the need to match the challenging demands of high-payload fraction, low cost, and also ensure reliability. This paper presents some of the important design requirements. An ideal velocity approach, which assumes various velocity losses, is generally followed for initial vehicle sizing. However, as this approach is approximate and sometimes incorrect, a new concept of accounting the drag and thrust losses during the atmospheric phase for conventional rockets and air-breathing launch vehicles using scramjet propulsion is evolved complementing the ideal velocity sizing approach. A simplistic two-dimensional trajectory simulation program with graphics for quick interactive design was developed for this purpose. The air-breathing launch vehicle trajectory is split into three flight phases. The sizing of the vehicle considering, especially, the intermediate air-breathing regime is also dealt with. A method to determine the maximum-load envelope expressed in terms of the product of flight dynamic pressure and angle of attack, namely Q-alpha, for all weather launches useful for initial design purposes is also suggested. The design program meant for initial design sizing purposes gives a quick insight on the vehicle performance prior to detailed design with minimum basic vehicle data for conventional rockets and also for air-breathing scramjet vehicles. The various design factors, such as optimum velocity requirement for two stage to orbit vehicles and the sizing requirement of the orbital stage after end of air-breathing phase, are also discussed through representative typical values highlighting the design sensitivities.

Temporal and spatial resolution of scattered and recoiled atoms for surface elemental and structural analysis

Developments in low-energy ion scattering over the past 10 years have led to new techniques for surface elemental and structural analyses. The fundamental physics involved in these new methods is summarized herein and some examples of the applications of the techniques are presented. Three major new developments are considered. First, time-of-flight scattering and recoiling spectrometry (ToF-SARS) takes advantage of ToF techniques to detect simultaneously both ions and fast neutrals that are scattered and recoiled from surfaces. Elemental analyses are obtained by application of binary collision theory, and structural analyses are performed by rotation of the sample in order to measure intensity changes as a function of incident and azimuthal angles. Second, scattering and recoiling imaging spectrometry (SARIS) takes advantage of a large position-sensitive microchannel plate detector, coupled with ToF techniques, to capture element-specific, time-resolved, spatial and intensity distributions of scattered and recoiled atoms from surfaces. These images combine atomic scale microscopy and spatial averaging because they are created from a macroscopic surface area but they are directly related to the atomic arrangement of the surface at the subnanoscale level; the features of the images are sensitive to changes in interatomic spacings at a level of <0.1 A. Third, a classical ion trajectory simulation program, called scattering and recoiling imaging code (SARIC), which is designed specifically for structural interpretation of ToF-SARS and SARIS data, has been developed. This program allows quantitative comparison of experimental and simulated data for surface structure determinations.

Scattering and recoiling imaging code (SARIC)

A new classical ion trajectory simulation program based on the binary collision approximation has been developed in order to support the results of time-of-flight scattering and recoiling spectrometry (TOF-SARS) and scattering and recoiling imaging spectrometry (SARIS). The code was designed to provide information directly related to the TOF-SARS and SARIS measurements and to operate efficiently on small personal computers. The calculation uses the Ziegler-Biersack-Littmark (ZBL) universal screening function or the Moliére screening function to simulate the three-dimensional motion of atomic particles and includes simultaneous collisions involving several atoms. For TOF-SARS, the program calculates the energy and time-of-flight distributions of scattered and recoiled particles, polar (incident) angle α-scans, and azimuthal angle δ-scans. For SARIS, the program provides images of the scattering and recoiling intensities in polar exit angle and azimuthal angle (β, δ)-space. A two-dimensional reliability factor ( R) has been developed in order to obtain a quantitative comparison of experimental and simulated images. Examples of simulations are presented for Ni{100}, {110} and {111} surfaces and a Pt{111} surface. The R-factor is used to quantitatively compare the simulated Pt{111} image to an experimentally emulated image.

SeGRAm: A practical and versatile tool for spacecraft trajectory optimization

An implementation of the Sequential Gradient/Restoration Algorithm, SeGRAm, is presented along with selected examples. This spacecraft trajectory optimization and simulation program uses variational calculus to solve problems of spacecraft flying under the influence of one or more gravitational bodies. It produces a series of feasible solutions to problems involving a wide range of vehicles, environments and optimization functions, until an optimal solution is found. The examples included highlight the various capabilities of the program and emphasize in particular its versatility over a wide spectrum of applications from ascent to interplanetary trajectories.

MATS - The mission analysis and trajectory simulation program

T Mission Analysis and Trajectory Simulation Program (MATS) is a general-purpose digital computer pragram written in FORTRAN IV.' It either has simulated or is potentially capable of simulating such diverse missions as Apollo, Mariner, Surveyor, Tiros, Comsat, Minuteman, and Sentinel. Key points of philosophy underlying the MATS design concept are: a phase-oriented sequencer controls the occurrence of events; the input parameters control the simulation; a bucket concept generalizes and minimizes data storage; and a modularized integrated systems approach permits planned evolution. The phase concept provides the mechanism whereby occurrence of events can be sequenced logically as in real-time situations. A phase is defined as a time interval corresponding to one of a continuous sequence of flight segments. A phase may be of zero duration to simulate an instantaneous inflight or logical event. Phase changes are treated as trajectory discrete points at which variables that affect the vehicle, environment or simulation may be introduced or varied. Examples of phase-oriented trajectory parameters are engine ignition and cutoff, attitude maneuvers or steering algorithms, and environment modifications; phase-oriented simulation parameters include integration method and stepsize control, output requests, logical phase manipulations, and iteration processes. The bucket concept minimizes the input storage requirements by identifying the data by phase, and storing it en masse; as each phase is initiated, the associated data are brought into active memory. The data are stored contiguously, so that no preassigned limits determine the type and volume active during any phase. Figure 1 schematically represents the program structure, which is based on a modular design concept.

Loader standardization for overlay programs

The overlay capability is described for four of the third generation computer systems: CDC-6000, GE-635, IBM-360, and UNIVAC-1108. A critique of the first three sytems is based on actual experience with a large overlaid trajectory simulation program; a short history and description of this program is presented. A standardization of minimum capabilities for loaders is recommended so that programs which must operate under more than one computer system may be easily converted and maintained. A proposal that overlay software incorporates a memory occupation specification concept instead of the conventional tree structure is delineated. This concept provides more efficient and cost-effective utilization of the memory as well as increasd flexibility in program structure.