Effects of Boundary Current on Electromagnetic Dispersion Characteristics for a Relativistic Electron Beam

With betatron oscillation characteristics of the electron beam and ion channel effect taken into account,dispersion characteristics of electrostatic modes and TM modes for a relativistic electron beam guided by ion channel are studied.Dispersion relations are derived and solved numerically to investigate the dependence of the dispersion characteristics for electrostatic modes and TM modes on the betatron oscillation frequency and the ratio of the relativistic electron beam radius to the waveguide radius.The effects of the boundary current on the dispersion characteristic of the TM modes and the interaction between the betatron modes and TM modes are analyzed.When considering the boundary current,for a strong ion channel,a new low-frequency branch of the TM modes arises and the interaction frequency between the betatron modes and the TM01modes is increased with the same parameters.

Essence of Photons and Dark Matters

What exactly are photons and dark matter? Modern physical theories do not explain them very well. In this paper, by extending the law of electromagnetic oscillation, the space particles and their operation law can also be obtained. The system of space particle theory is formed under the law of physics. The conclusion of the theory of space particles is quite consistent with many physical phenomena. There are no contradictions that can be found. According to the theory of space particles, there is an uneven space at the edge of an object, which has been proved by a series of experimental phenomena. The theory of space particles has revealed the essence of photons and dark matter. It has also revealed the relationship between space, mass, and energy. Space is a physical phenomenon.

Modeling of High-frequency Electromagnetic Oscillation for DC Fault in MMC-HVDC Systems

DC short-circuit faults pose a hazard to the operation of a modular multilevel converter(MMC)-based high voltage direct current(HVDC)system,necessitating reliable fault clearing solutions with rapid reaction.However,because the parasitic capacitances of the main equipment oscillate with the lumped inductances of the HVDC system,strong electromagnetic oscillations with multiple frequencies occur during clearance transients.These oscillations will disturb the HVDC system’s protection and control systems.Therefore,this paper focuses on the modeling of these oscillations.First,an equivalent circuit for the MMC-based HVDC system is proposed,taking into account the parasitic capacitances of the system’s major components,such as DC reactors,connecting cables,and DC circuit breakers(DCCBs).Second,four distinct oscillation stages are postulated based on action coordination of MMCs and DCCBs,and the associated analytical equations for the oscillation frequencies are derived.Third,a 200 kV MMC-based DC converter station is subjected to an 6ms/6kA pole-to-pole(PTP)short-circuit test.Electromagnetic oscillations have a frequency range of several kHz to several hundreds of kHz.The measured waveforms correspond well with simulated results,including the parasitic characteristics.Additionally,the relative errors between the simulated and measured frequencies are less than 5%.

The Droplet Evolution Trend and Purification Efficiency in ESR Process by Superimposing a Static Magnetic Field

The paper investigated the refinement effect on droplet size of Electroslag Remelting(ESR)Process by superimposing a transverse static magnetic field through physical simulation method.A transparent experimental model is built to visualize the ESR process under magnetic field,especially focusing on the formation and departure process of droplets on electrode tip.The results show that due to the interaction between alternating current and external transverse magnetic field,the resulting electromagnetic oscillation in the molten droplet and slag bath refined droplets remarkably, the higher the magnetic field intensity,the smaller the droplet size.However,there exists a suitable frequency of 10Hz for the current which will achieve an optimal effect of droplet's dispersing and refinement.Based on the theory of electromagnetic separation,a new mechanism of removing nonmetallic inclusions in ESR process is proposed.By a simplified circuit model,the inclusion removal efficiency is calculated and it proves that the refinement of droplets under magnetic field could increase the removal efficiency of nonmetallic inclusions in ESR significantly.