Research
All effects of Nature are only mathematical consequences of a small number of immutable laws.
- P. S. Laplace
Laboratory nanoflares from multiple braided plasma loops
We replicated braided plasma loops in the lab experiment. Nanoflare features are observed in the experiment when individual strands break. 7.6 keV X-rays are observed from 2 eV plasma. Tracking the sequence of loop formation, loop instability, and X-ray bursts provides insight into how macroscale phenomena (loop instability) can trigger microscale phenomena (X-ray bursts).
Yang Zhang, Seth Pree, and Paul M. Bellan
Nature Astronomy 7 (2023): 655–661.
Magnetic Rayleigh Taylor instability in an experiment simulating a solar loop
Magnetic Rayleigh Taylor instability is observed in solar loop experiment. The wavelength increases with the increseae of magnetic field as shown in the left figure (The top has a lower magnetic field compared with the bottom one). From these results, the variation of magnetic field strength may be a reason for observed differences in plume dynamics in solar prominences, so that prominences having weak magnetic field produce many small plumes while those with strong magnetic fields produce large plumes.
Yang Zhang, Pakorn Wongwaitayakornkul, and Paul M. Bellan The Astrophysical Journal Letters 889.2 (2020): L32.
Neutral-charged particle collisions as the mechanism for accretion disk angular momentum trasport
Left: N-body simulation of an accretion disk system with
Ions in Red, Electrons in Black, Neutrals in Blue.
We proposed a first-principle angular momentum transport mechanism based only on collisions between neutrals and charged particles. Ions and electrons drift to different radial directions under collisions with Kepler-motion neutrals and transport the canonical angular momentum of charged particles into the angular momentum of neutrals.
Yang Zhang and Paul M. Bellan
The Astrophysical Journal 930.2 (2022): 167.
Mechanism for generation of angular momentum in an astrophysical system
Rotation is a common feature of astrophysical bodies like protoplanetary disks, molecular clouds, and galaxies. Rotation is related to angular momentum. The origin of the angular momentum of astrophysical systems has not been resolved. Here we propose a simple angular momentum generation mechanism.
Yang Zhang and Paul M. Bellan
Mechanism for Generation of Angular momentum in an Astrophysical System. (Submitted)
Helical symmetric plasma equilibrium
Left: Helical nebula Credit to Wikipedia.
Braiding plasma structures with same-direction current have been broadly observed in the nature and experiments, but an equilibrium has not yet been given theoretically. We develop a Green-Function method to find the braided helical symmetric plasma equilibrium.
Yang Zhang and Paul M. Bellan
Magnetic Double Helix. (Submitted)
Properties of Local Modes in a Complex Plasma Chain with Foreign Particles
Local vibration modes when foreign particles are introduced into a dusty plasma chain are derived theoretically. It successfully predicts the random motion spectrum observed in a previous simulation and similar experiments.
Yang Zhang, Xiaogang Wang, and Bowen Li.
Physics of Plasmas 24.12 (2017): 123703.