arXiv subjects

M. Jia

Publications and source records attributed to M. Jia.

7 recordsLinked to original sources

arXiv2024

Suppression of Edge Localized Modes in ITER Baseline Scenario in EAST using Edge Localized Magnetic Perturbations

We report the suppression of Type-I Edge Localized Modes (ELMs) in the EAST tokamak under ITER baseline conditions using $n = 4$ Resonant Magnetic Perturbations (RMPs), while maintaining energy confinement. Achieving RMP-ELM suppression requires a normalized plasma beta ($\beta_N$) exceeding 1.8 in a target plasma with $q_{95}\approx 3.1$ and tungsten divertors. Quasi-linear modeling shows high plasma beta enhances RMP-driven neoclassical toroidal viscosity torque, reducing field penetration thresholds. These findings demonstrate the feasibility and efficiency of high $n$ RMPs for ELM suppression in ITER.

physics.plasm-ph↗

arXiv2023

From one to infinity: symmetries of integrable systems

Integrable systems constitute an essential part of modern physics. Traditionally, to approve a model is integrable one has to find its infinitely many symmetries or conserved quantities. In this letter, taking the well known Korteweg-de Vries and Boussinesq equations as examples, we show that it is enough to find only one nonlocal key-symmetry to guarantee the integrability. Starting from the nonlocal key-symmetry, recursion operator(s) and then infinitely many symmetries and Lax pairs can be successfully found.

nlin.SI↗

arXiv2023

Extension of ELM suppression window using n=4 RMPs in EAST

The q95 window for Type-I Edge Localized Modes (ELMs) suppression using n=4 even parity Resonant Magnetic Perturbations (RMPs) has been significantly expanded to a range from 3.9 to 4.8, which is demonstrated to be reliable and repeatable in EAST over the last two years. This window is significantly wider than the previous one, which is around q95=3.7pm0.1, and is achieved using n=4 odd parity RMPs. Here, n represents the toroidal mode number of the applied RMPs and q95 is the safety factor at the 95% normalized poloidal magnetic flux. During ELM suppression, there is only a slight drop in the stored energy (<=10%). The comparison of pedestal density profiles suggests that ELM suppression is achieved when the pedestal gradient is kept lower than a threshold. This wide q95 window for ELM suppression is consistent with the prediction made by MARS-F modeling prior to the experiment, in which it is located at one of the resonant q95 windows for plasma response. The Chirikov parameter taking into account plasma response near the pedestal top, which measures the plasma edge stochasticity, significantly increases when q95 exceeds 4, mainly due to denser neighboring rational surfaces. Modeling of plasma response by the MARS-F code shows a strong coupling between resonant and non-resonant components across the pedestal region, which is characteristic of the kink-peeling like response observed during RMP-ELM suppression in previous studies on EAST. These promising results show the reliability of ELM suppression using the n=4 RMPs and expand the physical understanding on ELM suppression mechanism.

physics.plasm-ph↗

arXiv2017

A novel type of rogue waves with predictability in nonlinear physics

Rogue waves named by oceanographers are ubiquitous in nature and appear in a variety of different contexts such as water waves, liquid Helium, nonlinear optics, microwave cavities, etc. In this letter, we propose a novel type of exact (2+1)-dimensional rogue waves which may be found in many physical fields described by integrable and nonintegrable models. This type of rogue waves are closely related to invisible lumps. Usually, a lump is an algebraically localized wave in space but visible at any time. Whence a lump induces a soliton, the lump will become invisible before or after a fixed time. If a bounded twin soliton is induced by a lump, the lump will become a rogue wave (or instanton) and can only be visible at an instant time. Because of the existence of the induced visible solitons, the rogue wave may be predictable in some senses. For instance, the height, the position and the arrival time of the rogue wave can be predictable. The idea is illustrated by the celebrate (2+1)-dimensional Kadomtsev-Petviashvili equation in its extended form.

nlin.PS↗

arXiv2009

Baroclinic equivalent and nonequivalent barotropic modes for rotating stratified flows

In strictly speaking, all the natural phenomena on the earth should be treated under rotating coordinate. The existence of baroclinic nonequivalent barotropic laminar solution for rotating fluids is still open though the laminar solutions for the irrotational fluid had been well studied. In this letter, all the possible equivalent barotropic (EB) laminar solution are firstly explored and all the possible baroclinic non-EB elliptic circulations and hyperbolic laminar modes are discovered. The baroclinic EB circulations (including the vortex streets and hurricane like vortices) possess rich structures because either the arbitrary solutions of arbitrary nonlinear Poison equations can be used or an arbitrary two-dimensional stream function is revealed. The discovery of the baroclinic non-EB modes disproves a known conjecture. The results may be broadly applied in atmospheric and oceanic dynamics, plasma physics, astrophysics and so on.

physics.flu-dyn↗

arXiv2008

Vortices, circumfluence, symmetry groups and Darboux transformations of the (2+1)-dimensional Euler equation

The Euler equation (EE) is one of the basic equations in many physical fields such as fluids, plasmas, condensed matter, astrophysics, oceanic and atmospheric dynamics. A symmetry group theorem of the (2+1)-dimensional EE is obtained via a simple direct method which is thus utilized to find \em exact analytical \rm vortex and circumfluence solutions. A weak Darboux transformation theorem of the (2+1)-dimensional EE can be obtained for \em arbitrary spectral parameter \rm from the general symmetry group theorem. \rm Possible applications of the vortex and circumfluence solutions to tropical cyclones, especially Hurricane Katrina 2005, are demonstrated.

nlin.PS↗

arXiv2005

Vortices, circumfluence, symmetry groups and Darboux transformations of the Euler equations

The Euler equation (EE) is one of the basic equations in many physical fields such as the fluids, plasmas, condense matters, astrophysics, oceanic and atmospheric dynamics. A new symmetry group theorem of the two dimensional EE is obtained via a simple direct method and the theorem is used to find \em exact analytical \rm vortex and circumfluence solutions. Some types of Darboux transformations (DTs) for the both two and three dimensional EEs are obtained for \em arbitrary spectral parameters \rm which indicates that the EEs are integrable and the Navier-Stockes (NS) equations with large Renoyed number are nearly integrable, i.e, they are singular perturbations of the integrable EEs. The possibility of the vortex and circumfluence solutions to approximately explain the tropical cyclones (TCs), especially, the Hurricane Andrew 1992, is discussed.

nlin.PS↗