arXiv subjects

Fang Ding

Publications and source records attributed to Fang Ding.

3 recordsLinked to original sources

arXiv2026

A Compact Reconfigurable Antenna for Single-RF-Chain Passive Multi-Target DOA Estimation

This work proposes a compact and hardware-efficient frequency- and radiation-pattern-reconfigurable antenna (FPRA) for passive multi-target direction-of-arrival (DOA) estimation using a single receive RF chain. The antenna consists of a sectorized circular patch loaded with 16 PIN diodes. By switching the diode states, the current-concentration boundary on the patch is shifted, enabling reconfiguration of both the operating frequency and radiation pattern. With a single receive RF chain, the proposed antenna achieves beam scanning from -40 degrees to 40 degrees and provides multiple operating frequencies across the S- and C-bands. Based on these reconfigurable observation states, radiation-pattern switching is used to emulate the spatial sampling of a conventional antenna array, while multi-frequency observations introduce phase diversity to reduce the correlation among echoes from multiple passive targets illuminated by the same transmitter. Experimental results demonstrate that the combined virtual spatial sampling and frequency diversity enable passive multi-target DOA estimation without a conventional antenna array or multiple receive RF chains. The proposed FPRA offers a compact and hardware-efficient sensing solution for future integrated sensing and communication (ISAC) systems.

physics.app-ph↗

arXiv2025

The effect of neon seeding on plasma edge transport in EAST

The effect of neon seeding on different transport mechanisms in EAST is investigated by analyzing SOLPSITER simulations. By evaluating the agreement between experimental observations and the performed simulations, four simulations are selected for a detailed analysis. In this analysis, it is shown that the presence of neon reduces the influence of drifts on the simulated profiles. In the simulation results, double peaked profiles/profiles with two valleys are observed at the divertor targets which can be explained by the parallel drift velocities These drifts move particles from the outboard towards the inboard side and, in that way, also increase the ionization sources at the inboard side. It is shown that Ne+ leaks towards the core making it difficult to perform experiments which contain as much neon as in the SOLPS-ITER simulations. In fact, the level of neon in the experiments is limited by the HL backtransition which takes place if higher order states of neon ionize in the core and cause in that way too much core radiation. Furthermore, the analysis of the radiated power profiles suggests that the presence of other radiators besides neon is important to bring the experiments into detachment. The ionization of deuterium is the most important neutral reaction present in the simulations. The amount of ionized deuterium is decreased when large amounts of neon are present and the anomalous transport is modified. Therefore, it is concluded that for the analyzed simulations, neon increases the radiated power fraction, decreases the deuterium ionization, increases the neutral friction, but does not manage to cause significant influence of deuterium recombination. As a consequence, volumetric recombination only plays a minor role in the studied simulations.

physics.plasm-ph↗

arXiv2020

Spatial distributions of Balmer series emissions in divertor plasmas with tungsten targets in different magnetic configurations on the EAST superconducting tokamak

The characteristics of wall recycling with different divertor configurations were investigated in this study, focusing on the observations of the spatial distributions of deuterium atomic emissions in the Balmer series (D_{\alpha}, D_{\beta}, D_{\gamma}, and D_{\delta}) with different magnetic field configurations in the Experimental Advanced Superconducting Tokamak. The observed D_{\alpha} and D_{\beta} emissions were primarily relatively close to the divertor targets, while the D_{\gamma} and D_{\delta} emissions were primarily relatively close to the X-point. The distributions of the emissions close to the divertor targets and X-point changed differently depending on the divertor configuration. These experimental results indicate that the linear comparison of parameters based on an assumption of similarity of profile shapes in different configurations is insufficient for understanding particle recycling in divertor plasmas. This is because the shape of the density profile of the recycled deuterium atoms and/or the electron density and temperature may change when the magnetic configuration is altered.

physics.plasm-ph↗