Three-Dimensional MHD Simulation of Caltech Plasma Jet Experiment: First Results
arXiv:1407.3498 · doi:10.1088/0004-637X/791/1/40
Abstract
Magnetic fields are believed to play an essential role in astrophysical jets with observations suggesting the presence of helical magnetic fields. Here, we present three-dimensional (3D) ideal MHD simulationsof the Caltech plasma jet experiment using a magnetic tower scenario as the baseline model. Magnetic fields consist of an initially localized dipole-like poloidal component and a toroidal component that is continuously being injected into the domain. This flux injection mimics the poloidal currents driven by the anode-cathode voltage drop in the experiment. The injected toroidal field stretches the poloidal fields to large distances, while forming a collimated jet along with several other key features. Detailed comparisons between 3D MHD simulations and experimental measurements provide a comprehensive description of the interplay among magnetic force, pressure and flow effects. In particular, we delineate both the jet structure and the transition process that converts the injected magnetic energy to other forms. With suitably chosen parameters that are derived from experiments, the jet in the simulation agrees quantitatively with the experimental jet in terms of magnetic/kinetic/inertial energy, total poloidal current, voltage, jet radius, and jet propagation velocity. Specifically, the jet velocity in the simulation is proportional to the poloidal current divided by the square root of the jet density, in agreement with both the experiment and analytical theory. This work provides a new and quantitative method for relating experiments, numerical simulations and astrophysical observation, and demonstrates the possibility of using terrestrial laboratory experiments to study astrophysical jets.
arXiv commentaccepted by ApJ 37 pages, 15 figures, 2 tables
References in corpus (20)
- Magnetic processes in a collapsing dense core. I Accretion and Ejection
- On Why Disks Generate Magnetic Towers and Collimate Jets
- The evolution of magnetic tower jets in the laboratory
- Magnetic Tower Outflows from a Radial Wire Array Z-pinch
- Poynting Jets from Accretion Disks
- A Laboratory Plasma Experiment for Studying Magnetic Dynamics of Accretion Discs and Jets
- Modeling the Large Scale Structures of Astrophysical Jets in the Magnetically Dominated Limit
- Faraday Rotation Measure Gradients from a Helical Magnetic Field in 3C 273
- Magnetar-Driven Magnetic Tower as a Model for Gamma-Ray Bursts and Asymmetric Supernovae
- Stability Properties of Magnetic Tower Jets
- Signatures of large-scale magnetic fields in AGN jets: transverse asymmetries
- On the jets, kinks, and spheromaks formed by a planar magnetized coaxial gun
- Episodic Magnetic Bubbles and Jets: Astrophysical Implications from Laboratory Experiments
- Structure of Magnetic Tower Jets in Stratified Atmospheres
- Magnetic Helix Formation Driven by Keplerian Disk Rotation in an External Plasma Pressure --- The Initial Expansion Stage
- Why current-carrying magnetic flux tubes gobble up plasma and become thin as a result
- A Numerical Model of Hercules A by Magnetic Tower: Jet/Lobe Transition, Wiggling, and the Magnetic Field Distribution
- Adaptive Optics Echelle Spectroscopy of [Fe II] 1.644 um in the RW Aur Jet: A Narrow Slice Down the Axis of the Flow
- Formation of X-Ray Cavities by the Magnetically Dominated Jet-Lobe System in a Galaxy Cluster
- Electromagnetic Fields in Jets