Showing papers in "Transactions of The Japan Society for Aeronautical and Space Sciences in 2001"
TL;DR: In this article, a Lyapunov-like approach is used to find the feedback control of a guidance law satisfying the L2 gain performance, which is derived from a linear time-varying mathematical model that describes the missile-target engagement.
Abstract: The guidance law design problem is formulated as a disturbance attenuation L2 gain control problem where target accelerations are regarded as unpredictable disturbances that are completely unknown, but bounded and guidance parameter errors are viewed as bounded control system parameter uncertainties. By using a Lyapunov-like approach to find the feedback control, a guidance law satisfying the L2 gain performance is derived from a linear time-varying mathematical model that describes the missile-target engagement. During the derivation of the guidance law, its robust stability is proved. Simulation results show that the presented guidance law provides strong robustness properties against heading error, guidance parameter errors, and target maneuvers; thus they obtain excellent miss-distance performance over the conventional realistic true proportional navigation guidance law.
49 citations
TL;DR: In this article, an attitude control law for astronomy or earth-observation satellites is presented, which requires highly stable attitude-pointing for observation and large-angle attitude maneuverability between successive observations.
Abstract: This paper presents an attitude control law for astronomy or earth-observation satellites, which require highly stable attitude-pointing for observation and large-angle attitude maneuverability between successive observations. In the control law, magnetic bearing wheels (MBWs) are used instead of conventional ball bearing wheels (BBWs). MBWs, whose rotors are magnetically suspended and thus have no mechanical contact, are low “microvibration” actuators for spacecraft attitude control systems. “All-axes-actively-controlled” MBWs, just as in a control-moment gyro (CMG), provide the capability of tilting the rotational axis besides the rotor-speed control, whose allowable tilt angle, however, is small (typically less than 3 degrees or so). In the proposed control law, multiple MBWs (which represent at least three for three axes control and preferably four for increased performance and hardware redundancy) of this type are adopted as actuators of attitude control. The capability of rotor tilting is applied for broadening control bandwidth to improve the pointing performances while maintaining stability of the control system. The rotational control of the wheels are used for the purpose of 1) accommodating for the excessive angular momentum (=rotor-tilt-angle increments) that may otherwise result in too much tilting of the rotor to cause rotor touchdown, and also 2) large-angle maneuvers of spacecraft attitude. Moreover, the increased degrees of control freedom of MBWs are advantageously used for a further decrement of rotor-tilt angle. The mathematical formulation of our proposed control law is presented, and the results of the numerical simulation on the control performance are also shown.
22 citations
TL;DR: The first stage of the H-2 rocket used a 110-ton thrust liquid oxygen, liquid hydrogen, pump-fed engine, the LE-7, which required high-pressure and high-power liquid oxygen and liquid hydrogen turbopumps to achieve the two-stage combustion cycle in which the combustion pressure is around 13 MPa as mentioned in this paper.
Abstract: The first stage of the H-2 rocket used a 110-ton thrust liquid oxygen, liquid hydrogen, pump-fed engine, the LE-7. This engine required high-pressure and high-power liquid oxygen and liquid hydrogen turbopumps to achieve the two-stage combustion cycle in which the combustion pressure is around 13 MPa. Furthermore, it was very important to operate both turbopumps at higher rotational speeds to obtain a smaller, lighter-weight engine because the LE-7 had not low-speed, low-pressure pumps ahead of both the main pumps. The present paper shows the design, test results, and modifications that had been performed until a flight-type liquid oxygen turbopump for the LE-7 engine was completed. The liquid oxygen turbopump had been developed by the use of three models, that is, research, prototype, and flight models.
21 citations
14 citations
TL;DR: In this paper, a theoretical attempt is made to describe local and propagating-wave disturbances with the method of complex characteristics and examine whether the so-called absolute instability can occur in three-dimensional boundary layers whose basic state and stability properties vary in a specific direction of space.
Abstract: A theoretical attempt is made to describe local and propagating-wave disturbances with the method of complex characteristics and to examine whether the so-called absolute instability can occur in three-dimensional boundary layers whose basic state and stability properties vary in a specific direction of space. With a complex dispersion relation including one space variable, zeros of the complex group velocity are found not to produce such a drastic phenomenon as the absolute instability predicted in the parallel-flow problems studied so far. This is because the group velocity in the neighborhood of a zero varies in proportion to the square root of the distance from the zero.
14 citations
TL;DR: In this paper, a simplified system of stability equations is presented to show if the conditions of absolute instability can be satisfied in a simple rotating disk flow with three-dimensional boundary layers, and the results indicate no such particular amplification of disturbances near a zero of the complex group velocity.
Abstract: Rotating-disk flow is taken as a typical example of three-dimensional boundary layers. Numerical computations of localized disturbances according to the propagation theory given in Part 1 are made with a simplified system of stability equations to show if the conditions of absolute instability can be satisfied in this simple flow. The results indicate no such particular amplification of disturbances near a zero of the complex group velocity. It is also shown how initially localized disturbances propagate and develop into quite a large amplification of some limited wave-number components at a downstream station.
12 citations
TL;DR: In this paper, the performance and energy balance of a CW laser thruster were numerically computed, and the estimated energy conversion efficiency was 23% and the rest of the input power was lost as radiation from the laser and also carried by the laser beam passing through the LSP.
Abstract: Laser propulsion powered by a CW laser has been studied. Thruster performance and energy balance in the thruster were numerically computed. Laser beam optics, inverse-bremsstrahlung absorption, ionization/recombination reactions, radiation, heat conduction, and convection have been modeled. Computational stiffness resulting from the very small flow speed has been overcome by using a flux vector splitting implicit scheme with a large CFL number. The computed positions of the Laser Sustained Plasma (LSP) in the thruster show good agreement with the measured ones. The estimated energy conversion efficiency was 23%, and the rest of the input power was lost as radiation from the LSP and also carried by the laser beam passing through the LSP.
10 citations
9 citations
TL;DR: In this paper, a sliding mode controller was used for suppressing two-dimensional incompressible flow flutter problems in which aerodynamic uncertainties and structural nonlinearity were incorporated. But the sliding mode controllers were not considered for the control inputs of the leading and trailing edge control surfaces.
Abstract: This paper applies a sliding mode controller for suppressing two-dimensional incompressible flow flutter problems in which aerodynamic uncertainties and structural nonlinearity are incorporated. To consider the aerodynamic uncertainties, the steady aerodynamic theory is regarded for the controller design, although the quasi-steady aerodynamic theory is employed in numerical simulation. The structural nonlinearity is included about pitch motion to make a limit cycle oscillation appearing in flutter phenomenon. The control inputs are leading and trailing edge control surfaces. At a velocity of 20m/s, the sliding mode controller is designed to suppress the initial response within 1 second while the uncontrolled wing shows limit cycle oscillation. Furthermore, the sliding mode controller shows robust characteristics in a wide range of the flow velocity. These results indicate that the sliding mode controller is effective for suppressing the flutter problems that have aerodynamic uncertainties and structural nonlinearity.
8 citations
TL;DR: In this article, the authors analyzed the fully-developed pilot-induced oscillation (PIO) as a worst case for the safety of piloted airplanes, including actuator rate limiting, feedback control loop, and pilot delay by using describing function method.
Abstract: Fully-developed pilot-induced oscillation (PIO) is an important issue to be solved in the development of modern fly-by-wire flight control systems. In this paper, the fully-developed PIO is analyzed as a worst case for the safety of piloted airplanes, including actuator rate limiting, feedback control loop, and pilot delay by using describing function method. It is shown that the predictions obtained with this method closely match results of the simulation in the frequency and the amplitude of the PIO limit cycle. And it demonstrates that the feedback control loop has a positive effect on PIO and decreases amplitude of the oscillation.
8 citations
TL;DR: In this article, a definition of wavelet multiresolution autocorrelation based on the discrete wavelet transform is developed. And a new identification technique that combines the wavelet multi-resolution analysis combined with the waveletsolution autoregressive analysis is proposed.
Abstract: To evaluate coherent structures in the dimension of time and scale, a definition of wavelet multiresolution autocorrelation based on the discrete wavelet transform is first developed. Then a new identification technique that combines the wavelet multiresolution analysis combined with the wavelet multiresolution autocorrelation analysis is proposed. By analyzing u- and v-components of fluctuating velocity, the coherent structure and its scales can be identified when larger local amplitude fluctuation and stronger autocorrelation appear at the same wavelet level. For a turbulent jet at a downstream distance of x/d=6, the coherent structures with frequency 39Hz can be deduced about times 0.29, 0.53, 0.6, and 0.67s. This also represents the passing of eddies through the shear layer and concentration of the energy of the flow at these instants.
TL;DR: In this paper, the stability of compressible three-dimensional boundary layers to stationary disturbances is examined on the basis of the linear stability theory, and it is shown that the boundary layer becomes unstable to stationary 3D modes when the cross-flow velocity exceeds a rather small threshold of less than 1% of the external flow velocity.
Abstract: The stability of compressible three-dimensional boundary layers to stationary disturbances is examined on the basis of the linear stability theory. Comparisons of stability characteristics are made between the subsonic and supersonic boundary layers at the edge Mach numbers 0.2 and 2.0, respectively. The result shows that the boundary layer becomes unstable to stationary three-dimensional modes when the cross-flow velocity exceeds a rather small threshold of less than 1% of the external flow velocity. Important to note that the critical Reynolds number for stationary modes does not strongly depend on the Mach number. It is also found that the wavelength of the most amplified stationary three-dimensional mode is four or five times the boundary-layer thickness, not depending on the magnitude of cross-flow velocity both for the subsonic and supersonic flows.
TL;DR: In this paper, the propulsion dynamics of a waterjet rocket is analyzed by simultaneously solving the momentum and the newly derived generalized power equations to predict its flight histogram, computationally, and convolutionally.
Abstract: The launching of a waterjet rocket has been a very popular idea in recent years. Its basic propulsion principle makes use of the high-pressurized air inside the rocket’s main body to swiftly expel the water out of the nozzle and thus generate thrust. The waterjet rocket is characterized with nature, interest, combustionlessness, environmental friendliness, simplicity, and minimal cost. Moreover, it is a very good science model for propulsion analysis, design, experiment, and education because of an abundance of easily adjustable key parameters. This model also features separately stored energy and mass of the propellant, in contrast to a conventional rocket. However, related literature shows that no in-depth theoretical analysis of the waterjet rocket has been attempted for various reasons. In this research, the propulsion dynamics of a waterjet rocket is analyzed by simultaneously solving the momentum and the newly derived generalized power equations to predict its flight histogram, computationally, and convolutionally. This integrated energy approach synthesizes the internal and external dynamics analyses together and ingeniously takes full advantage of the clear power supply of pressurized air in a waterjet rocket. The analysis results are generally agreeable with the experimental flight data. While the new power equation herein gives a complete spectrum of physical parameters to be manipulated, there will be wider room in quest of better rocket propulsion performance, especially through the heuristic research of this versatile but affordable waterjet rocket.
TL;DR: In this article, a method of complex characteristics is used to describe four kinds of localized disturbances in the boundary layer on a flat plate, including vibrating ribbon, two-dimensional pulse through a slit parallel to the leading edge, continuous excitement through a small hole on the plate, and an instantaneous jet from the same hole.
Abstract: The method of complex characteristics is used to describe four kinds of localized disturbances in the boundary layer on a flat plate. The disturbances are those introduced by vibrating ribbon, two-dimensional pulse through a slit parallel to the leading edge, continuous excitement through a small hole on the plate, and an instantaneous jet from the same hole. The corresponding four equation systems are numerically solved to show fundamental properties of these disturbances. It is also intended to estimate quantitative effects of the leading-edge sweep angle and of the boundary-layer nonparallelism on the development of a three-dimensional wave packet.
TL;DR: In this article, a nonlinear optimal state feedback control is designed for the deployment and retrieval of a tethered satellite in the orbital plane, where the mass and flexibility of the tether are neglected and the controlled system is expressed by a bilinear state equation.
Abstract: Nonlinear optimal state feedback control is designed for the deployment and retrieval of a tethered satellite in the orbital plane. The mass and flexibility of the tether are neglected, and the controlled system is expressed by a bilinear state equation. To stabilize the system asymptotically, the receding horizon control is applied with the terminal state constrained to be zero. As a practical approach to the problem, the time-dependent penalty function method is employed to achieve the terminal constraint asymptotically, and an algorithm is derived so that an increase of the terminal penalty will cause no numerical difficulty. The effectiveness and robustness of the present approach are confirmed in numerical simulations.
TL;DR: The fuzzy control proved to provide effective flexible application to aircraft stability augmentation by showing good control performance to improve the dutch roll characteristics under all flight conditions for both small high-speed aircraft and large transport aircraft without the parameter changes.
Abstract: The fuzzy control law to improve dutch roll characteristics of aircraft was designed and its control performance was evaluated. First, the control law was designed for a small-high speed aircraft at low altitude and low-speed flight conditions. The control law was then applied to flight conditions from minimum speed to supersonic speed and from sea level to high altitude. The control performance for these conditions was evaluated. Furthermore, this control law was adapted to a large transport aircraft with no parameter changes. The evaluation showed good control performance to improve the dutch roll characteristics under all flight conditions for both small high-speed aircraft and large transport aircraft without the parameter changes. This means that the fuzzy control proved to provide effective flexible application to aircraft stability augmentation. If an aircraft in actual flight is in strong air turbulence, inputs to the fuzzy controller may exceed the limit of its effective range. To cope with this problem, the countermeasures were introduced, their methods tested, and their effectiveness proved.
TL;DR: In this paper, the attitude reference system with a one-degree-of-freedom platform was developed using the rotation angle defined in this paper and two parameters showing the rotational axis orientation.
Abstract: It is well known as the coning effect that even the motion around an axis with no angular rate results in the residual rotation when it resumes the original orientation. However, there has been little investigation concerning the residual rotation when the motion is not closed and does not resume the original orientation. A definition of rotation angle is newly proposed in this paper, and the calculation method of the rotation angle is shown. The new attitude reference system with a one-degree-of-freedom platform was developed using the rotation angle defined in this paper and two parameters showing the rotational axis orientation. The attitude reference system was actually onboard the M-rocket, and it worked well.
TL;DR: In this article, an electrodynamic tether was used to deorbit a spent H-II upper stage to reduce space debris, where the induced current flows through the tether wire by the tether motion that intersects the geomagnetic field, and the Lorentz force is induced in the opposite direction of tether motion, namely, the direction of the decelerating system.
Abstract: This study proposes an application of the electrodynamic tether to deorbit a spent H-II upper stage to reduce space debris. In such an application, the induced current flows through the tether wire by the tether motion that intersects the geomagnetic field, and the Lorentz force is induced in the opposite direction of tether motion, namely, the direction of the decelerating system, by the interaction between this induced current and the geomagnetic field. The concept is basically the same as that of a ProSEDS space experiment, which is proposed by NASA’s Marshall Space Flight Center. But the main difference is its orbit. The orbit of spent H-II upper stage is ellipse, although the orbit of ProSEDS is circular. So the operation and dynamics are different compared with those of ProSEDS. In this study, the performance of an H-II upper stage deorbit system by electrodynamic tether is analyzed by the mission analysis model, and the presumable dynamics of this system is also shown. The results show that this system can deorbit an H-II upper stage in a few months, but there is a possibility that the performance of deorbit will degrade if a rotation of the tether system is occurred.
TL;DR: In this article, the authors used the moving horizon states estimation (MHSE) method to estimate the states of nonlinear aircraft equation of motion from a dynamic maneuver's flight test data.
Abstract: This paper presents the application of the moving horizon states estimation (MHSE) method to estimate the states of nonlinear aircraft equation of motion from a dynamic maneuver’s flight test data. To determine the optimum solution of minimizing the performance index, a Quasi-Newton or gradient method is used. The present method also uses the Armijo’s line search gradient to guarantee the solution/estimation to converge faster to the global optimum estimate. The MHSE method is applied to flight test data of N250 PA-1 aircraft for parameter identification and flight path reconstruction. The result of estimation is also used to evaluate the accuracies of the measurement systems.
TL;DR: It is shown that high flexural rigidity of elastic panels improves the synchronism of the deployment, and the strain energy of each module depends on constraints of the module.
Abstract: Deployment behavior of modularized space structures is analyzed from the viewpoint of dynamic and simultaneous deployment. Actuators, which are attached to each substructure individually, realize the decentralized and simultaneous deployment. Elastic panels with double-accordion folding pattern are examined as an example of modularized structures. Corresponding analytical model is derived from the hybrid variational principle. At first, the deployment behavior of one module is simulated numerically to analyze the deployment characteristics of the double-accordion folding. The influences of panels’ shape and flexural rigidity on the deployment characteristics are clarified. Furthermore, the deployment behavior of multi modules is simulated numerically to analyze the synchronism of the deployment. It is shown that high flexural rigidity of elastic panels improves the synchronism of the deployment, and the strain energy of each module depends on constraints of the module. The synchronism of the deployment and the distribution of the strain energy are then considered qualitatively for general dynamic and simultaneous deployment.
TL;DR: In this article, the potential function guidance is applied to the autonomous formation-keeping of the eccentricity separation in the co-located many-satellite system, and the acceleration resulting from the continuous and throttled thrust is formulated as a function of positions and velocities of all satellites.
Abstract: The potential-function guidance is applied to the autonomous formation-keeping of the eccentricity separation in the co-located many-satellite system. The acceleration resulting from the continuous and throttled thrust is formulated as a function of positions and velocities of all satellites. If these state variables are measured by on-board sensors, the maneuvering schedule can be computed in the respective satellites. A numerical simulation affirms the validity of the control.
TL;DR: A Cartesian grid is used in this paper, where its non-body-fitted property allows the grid to stay stationary while the bodies move across it, which may lead to a significant saving of computational cost.
Abstract: Flow simulation around a moving body is a challenging problem, especially when there is more than one body moving relative to each other. To tackle this problem, a Cartesian grid is used in this paper, where its non-body-fitted property allows the grid to stay stationary while the bodies move across it. As a result, it requires only local grid modification in the vicinity of body surface, which may lead to a significant saving of computational cost. On the other hand, the body-fitted grids such as structured and tetrahedral-based unstructured grids move with the body; thus global grid modification is necessary during the movement. In the present study we devised a new implementation procedure for an existing two-dimensional cell-merging method to overcome the problem of conservation regarding gas dynamic properties, a problem caused by body movement across a grid. The present method may have a better potential for extension to 3D. It is based on our previous algorithm developed for a 3D unstructured Cartesian grid and was successfully applied to several test cases in this study. In particular, the efficiency of the method is greatly improved by employing a tree-based data structure to reduce the time to find body panels during computation of the cell’s geometrical properties.
TL;DR: In this article, a three-dimensional anisotropic Cartesian grid adaptation method has been developed to improve computational efficiency by reducing the number of cells, which can produce cells with unlimited aspect ratio while keeping the grid reasonably smooth.
Abstract: A three-dimensional anisotropic Cartesian grid adaptation method has been developed to improve computational efficiency by reducing the number of cells. The method can produce cells with unlimited aspect ratio while keeping the grid reasonably smooth. A test case of 2D supersonic flow around a cylinder shows that the number of cells is reduced to one to two orders of magnitude less than that of the corresponding isotropic grid, because all cells can extend in the spanwise direction. It is also found that the present method is not sensitive to variation in initial grid. Furthermore, a test case of ONERA M6 wing in transonic flow shows good agreement with experimental data, where the anisotropic grid needs only about half of the total number of cells in an equivalent isotropic grid.
TL;DR: In this paper, the aerodynamic heating of a super orbital reentry capsule for MUSES-C is numerically studied by using full viscous-shock-layer (VSL) equations with an 11 air-species model.
Abstract: The aerodynamic heating of a super orbital reentry capsule for MUSES-C is numerically studied by using full viscous-shock-layer (VSL) equations with an 11 air-species model. With a three-temperature model, the thermal nonequilibrium effect is considered. Temperatures, chemical species, and energy exchange rates at three typical altitudes, 74 km, 64 km, and 54 km, are discussed to understand how thermochemical nonequilibrium phenomena change along the reentry trajectory path. The convective and radiative heat fluxes to the wall of the MUSES-C capsule with a 0.2 m nose radius are examined under both noncatalytic wall (NCW) and fully catalytic wall (FCW) conditions. The maximum heat fluxes estimated for FCW and NCW are 8.7 MW/m2 and 6.1 MW/m2 at the altitude of 56 km. The radiative heat flux at the stagnation point of the capsule has also been calculated, and the maximum radiative heat flux of 0.9 MW/m2 has been found at the altitude of 62 km. The intensity of UV and VUV spectra are extremely intense; thus UV and VUV spectra mainly contribute to the radiative heat flux.
TL;DR: The Semi-Lagrangian (SL) scheme developed for incompressible Navier-Stokes equations written in generalized coordinates has been explored to accurately solve the high Reynolds number flows as discussed by the authors.
Abstract: The Semi-Lagrangian (SL) scheme developed for incompressible Navier-Stokes equations written in generalized coordinates has been explored to accurately solve the high Reynolds number flows. The instability related to the advection term of the Navier-Stokes equations is classified into linear instability and nonlinear instability. The former is controlled by the CFL condition, and the latter is due to the aliasing error. The linear instability is naturally eliminated by employment of the SL scheme. The Kawamura scheme is creatively applied to approximate the first derivatives appearing in the Hermite interpolation function to remove the nonlinear instability. The resulting numerical scheme is unconditionally stable for incompressible flows at all Reynolds numbers. Accurate numerical solutions of the unsteady flow around a 2D circular cylinder at Reynolds numbers below 100,000 have been carried out. It was found that this flow has a wide range of wave number modes. Numerous grid numbers and a small time step length must be used to guarantee the accuracy. Furthermore, a very long time average should be conducted to compare the data with the experimental measurement.
TL;DR: In this paper, an actuator system composed of wheel-rotor drive motors and magnetic torquers driven by a newly devised cooperative drive law was proposed to improve the attitude-pointing stability of astronomy satellites/and earth-observation satellites.
Abstract: As pointing requirements of astronomy satellites become more demanding, a conventional momentum-exchange scheme for attitude-pointing control is sometimes not enough to satisfy stringent stability requirements. This paper presents a new attitude control system for improving the attitude-pointing stability of astronomy satellites/and earth-observation satellites. In our proposed control system, an actuator system is composed of wheel-rotor drive motors and magnetic torquers driven by a newly devised “cooperative drive law.” The pointing stability is improved by torque control of the actuator system so that the total torque acting on the satellite body is minimized with the use of disturbance observers and in a way that shortcomings of the actuators are compensated for by each other. In the torque control, attitude control and momentum management are both treated consistently. In this paper, the mathematical formulation of our proposed scheme is presented, and the results of numerical simulations are also presented to demonstrate the stability improvement.
TL;DR: In this article, the plume flow field of an arcjet thruster with hydrazine decomposed gas as the propellant has been numerically analyzed to reveal a backflow field, using Direct Simulation Monte Carlo (DSMC).
Abstract: The plume flow field of an arcjet thruster with hydrazine decomposed gas as the propellant has been numerically analyzed to reveal a backflow field, using Direct Simulation Monte Carlo (DSMC). Hydrazine decomposed gas is approximated by a mixture of gas composed of N2, H2, and H. Four different nozzle lip shapes have been prepared to investigate their effects on the backflow, and species existing in the backflow have also been examined. The present results of mass flux at various angles measured from the plume axis have been compared with experiments, and a qualitatively fairly good agreement has been obtained.
TL;DR: In this article, the authors designed a terrain-following controller with a basic state feedback and a feed-forward compensation for future altitude information, regarding the wind as a constant signal.
Abstract: We adopted optimal preview control methodology to design a terrain-following controller for a cruise missile. In this methodology, tracking errors and control increments are both considered in a quadratic penalty function. An augmented error system that involves future command inputs is built. Thus the preview control problem can be formulated as an optimal regulator problem. Integrating the general optimal servo system with preview feed-forward compensations that respectively feed forward future command inputs and future disturbances produces an optimal preview servo system. In the terrain-following system, the flight altitude of a cruise missile is the command input, and its future information can be known a priori. The wind is viewed as the disturbance in the system and is not previewable. Thus we designed a terrain-following controller with a basic state feedback and a feed-forward compensation for future altitude information, regarding the wind as a constant signal. Simulation results show that the performance of the terrain-following system with such an optimal preview controller is improved dramatically.
TL;DR: In this paper, the experimental and numerical studies of a laboratory model of the low-power nitrogen arcjet thruster that was developed to provide thruster performance data to validate numerical results were described.
Abstract: This paper describes the experimental and numerical studies of a laboratory model of the low-power nitrogen arcjet thruster that was developed to provide thruster performance data to validate numerical results. The arcjet thruster was operated by using a nozzle 1.0mm in constrictor diameter. Thrust and input power were measured for various arc currents and nitrogen mass flow rates. The operation was done at power levels ranging from 156W to 540W and nitrogen mass flow rates from 5mg/s to 30mg/s. Typical specific impulse obtained in the experiment was 188s at 542W. Numerical simulation was conducted by using the physical model of a thermochemical nonequilibrium gaseous flow, a two-temperature model consisting of heavy particle and electron temperatures. The flowfield equations were numerically solved by combining with the Maxwell’s equation and the generalized Ohm’s law. It is shown that the predicted thruster performance is higher than the experimental data for the specific impulse, and the possible causes for this trend are discussed.