An algorithm to obtain data-driven models of oscillatory phenomena in plasma space propulsion systems is presented, based on sparse regression (SINDy) and Pareto front analysis. The algorithm can incorporate physical constraints, use data bootstrapping for additional robustness, and fine-tuning to different metrics. Standard, weak and integral SINDy formulations are discussed and compared. The scheme is benchmarked in the case of breathing-mode oscillations in Hall effect thrusters, using PIC/fluid simulation data. Models of varying complexity are obtained for the average plasma properties, and shown to have a clear physical interpretability and agreement with existing 0D models in the literature. Lastly, the algorithm applied is also shown to enable the identification of physical subdomains with qualitatively different plasma dynamics, providing valuable information for more advanced modeling approaches.
Consuming long-range interplanetary medium with fuel for driving plasma thrust is vital. Methods of capturing the space environment depending on its density and the ship velocity are indispensable issues to extract the space environment as a propellant. This matter of neutral fluxes would use solar radiation to create ionization in a plasma thruster. Extracting propellant at certain ranges look extremely promising where a low thrust device operates continuously to deliver a celestial target close at the speed of light. However, at longer distances, the density of space rapidly diminishes and i…
This paper provides perspectives on recent progress in the understanding of the physics of devices where the external magnetic field is applied perpendicularly to the discharge current. This configuration generates a strong electric field, which acts to accelerates ions. The many applications of this set up include generation of thrust for spacecraft propulsion and the separation of species in plasma mass separation devices. These ExB plasmas are subject to plasma-wall interaction effects as well as various micro and macro instabilities, and in many devices, we observe the emergence of anomalo…
Wake-mediated propulsion of an upstream particle in two-dimensional plasma crystals
在模拟和理论中解释了由Du等人[Phys. Rev. E 89，021101（R）（2014）]实验观察到的二维等离子体晶体的两个相邻行的通道中的“额外”粒子的尾流介导的推进。我们使用点状离子尾流电荷的简单模型来在模拟中重现这种有趣的效应，从而可以进行详细的研究并更深入地了解潜在的动力学。我们表明，粒子相互作用的非互易性，由于唤醒电荷，是负责打破对称的通道，使持久的自我推进运动的额外粒子。我们发现很好的协议与我们的理论考虑和实验的终端外粒子速度。
This work presents a more detailed analysis of the process of magnetic reconnection as promising ion beam accelerator mechanism with possible applications in laboratory plasmas and, more importantly, in the plasma propulsion field. In a previous work, an introductory study on this subject was already carried out, yet under the adoption of relevant approximations, such as the limitation to 2.5D simulations and the especially use of Hydrogen plasma as a propellant, whose element is rarely considered in the real scenario. Also, the analysis mainly focussed on studying the physical content of the …
Challenging space missions include those at very low altitudes, where the atmosphere is source of aerodynamic drag on the spacecraft. To extend such missions lifetime, an efficient propulsion system is required. One solution is Atmosphere-Breathing Electric Propulsion (ABEP). It collects atmospheric particles to be used as propellant for an electric thruster. The system would minimize the requirement of limited propellant availability and can also be applied to any planet with atmosphere, enabling new mission at low altitude ranges for longer times. Challenging is also the presence of reactive…
The inductively-heated plasma generator IPG6-B at Baylor University has been established and characterized in previous years for use as a flexible experimental research facility across multiple applications. The system uses a similar plasma generator design to its twin-facilities at the University of Stuttgart (IPG6-S) and the University of Kentucky (IPG6-UKY). The similarity between these three devices offers the advantage to reproduce results and provides comparability to achieve cross-referencing and verification. Sub- and supersonic flow conditions for Mach numbers between $Ma = 0.3 - 1.4$…
The measurement of the propulsion of metallic microdroplets exposed to nanosecond laser pulses provides an elegant method for probing the ablation pressure in dense laser-produced plasma. We present the measurements of the propulsion velocity over three decades in the driving Nd:YAG laser pulse energy, and observe a near-perfect power law dependence. Simulations performed with the RALEF-2D radiation-hydrodynamic code are shown to be in good agreement with the power law above a specific threshold energy. The simulations highlight the importance of radiative losses which significantly modify the…
This paper focuses on a survey of experimental data related to radiation into CO$_2$ plasma flows, which are encountered during Mars and Venus entries. The review emphasizes on VUV and IR radiation, since recent experimental efforts has been devoted to these wavelength ranges. The main objective of the study is to identify the most attractive datasets for future cross-check comparisons with the results obtained during future test campaigns with ESTHER shock-tube. The survey accounts for the results obtained in shock-tubes, expansion tube and plasma arc-jets for Mars and Venus test campaigns. T…
Proton radiography is a widely-fielded diagnostic used to measure magnetic structures in plasma. The deflection of protons with multi-MeV kinetic energy by the magnetic fields is used to infer their path-integrated field strength. Here, the use of tomographic methods is proposed for the first time to lift the degeneracy inherent in these path-integrated measurements, allowing full reconstruction of spatially resolved magnetic field structures in three dimensions. Two techniques are proposed which improve the performance of tomographic reconstruction algorithms in cases with severely limited nu…
Laser ablation plasma thrusters are an emerging space propulsion concept that provides promise for lightweight payload delivery. Predicting the lifetime and performance of these thrusters hinges on a comprehensive characterization of the expansion dynamics of the ablated plasma plume. While state-of-the-art techniques for simulating plasmas are often particle-based, a grid-based direct kinetic solver confers advantages in such a transient and inhomogeneous problem by eliminating statistical noise. A direct kinetic solver including interparticle collisions is employed on a plume expansion model…
Embedding physical symmetries into machine-learned reduced plasma physics models via data augmentation
University of California, Los Angeles（加州大学洛杉矶分校）；Universidade de Lisboa（里斯本大学）；Mani L. Bhaumik Institute for Theoretical Physics, University of California at Los Angeles（加州大学洛杉矶分校马尼·L·巴乌米克理论物理研究所）
A sustainable burn platform through inertial confinement fusion (ICF) has been an ongoing challenge for over 50 years. Mitigating engineering limitations and improving the current design involves an understanding of the complex coupling of physical processes. While sophisticated simulations codes are used to model ICF implosions, these tools contain necessary numerical approximation but miss physical processes that limit predictive capability. Identification of relationships between controllable design inputs to ICF experiments and measurable outcomes (e.g. yield, shape) from performed experim…
Low frequency ionization oscillations involving plasma and neutral density (breathing modes) are the most violent perturbations in Hall thrusters for electric propulsion. Because of its simplicity, the zero-dimensional (0-D) predator-prey model of two nonlinearly coupled ordinary differential equations for plasma and neutral density has been often used for the characterization of such oscillations and scaling estimates. We investigate the properties of its continuum analog, the one-dimensional (1-D) system of two nonlinearly coupled equations in partial derivatives (PDE) for plasma and neutral…
Interpretive Modeling of plasma evolution during fueling experiments at CMFX
MIT Plasma Science and Fusion Center（麻省理工学院等离子体科学与聚变中心）；University of Maryland Baltimore County（马里兰大学巴尔的摩县分校）；University of Maryland College Park（马里兰大学帕克分校）
In magnetic confinement fusion devices, the equilibrium configuration of a plasma is determined by the balance between the hydrostatic pressure in the fluid and the magnetic forces generated by an array of external coils and the plasma itself. The location of the plasma is not known a priori and must be obtained as the solution to a free boundary problem. The partial differential equation that determines the behavior of the combined magnetic field depends on a set of physical parameters (location of the coils, intensity of the electric currents going through them, magnetic permeability, etc.) …
A Deterministic Ionization Algorithm for the OSIRIS Particle-in-Cell Framework
Gérard Mourou Center for Ultrafast Optical Science, University of Michigan（密歇根大学 Gérard Mourou 超快光学科学中心）；GoLP/IPFN, Instituto Superior Técnico, Universidade de Lisboa（里斯本大学高等技术学院 GoLP/IPFN）
Toward a Multimodal Foundation Model for Plasma State Reconstruction
School of Physics（物理学院）；Georgia Institute of Technology（佐治亚理工学院）；Boston University（波士顿大学）；Princeton Plasma Physics Laboratory（普林斯顿等离子体物理实验室）；Princeton University（普林斯顿大学）；Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室）；Carnegie Mellon University（卡内基梅隆大学）
Using particle-in-cell simulations of relativistic laser plasma wakes in the presence of an external magnetic field, we demonstrate that there exists a parameter window where the dynamics of the magnetized wake channel are largely independent of the laser wavelength $λ_{\rm las}$. One condition for this manifestation of "limited similarity" is that the electron density $n_{\rm e}$ is highly subcritical, so that the plasma does not affect the laser. The freedom to choose a convenient laser wavelength can be useful in experiments and simulations. In simulations, an up-scaled wavelength (and, thu…
