Numerical study of the radio-frequency biased accelerating system in ion thrusters

A 2D-3V implicit immersed-finite-element particle-in-cell(IFE-PIC) model is introduced to investigate the radio-frequency(RF) self-bias accelerating system applied in the RF ion thruster.A set of holes in a two-grid system with slit apertures is simulated in Cartesian coordinates. The characteristics of the plasma plume, such as the ion density, the neutralization rate and the ion and electron current density were investigated for different RF voltage amplitudes(600-1200V) and frequencies(6-30 M...     

Experimental study of a neutralizer-free gridded ion thruster using radio-frequency self-bias effect

An experimental study on the quasi-neutral beam extracted by a neutralizer-free gridded ion thruster prototype was presented. The prototype was designed using an inductively coupled plasma source terminated by a double-grid accelerator. The beam characteristics were compared when the accelerator was radio-frequency(RF) biased and direct-current(DC) biased. An RF power supply was applied to the screen grid via a blocking capacitor for the RF acceleration, and a DC power supply was directly connec...     

汽轮机典型负荷陡变现象的故障类别及机理分析

汽轮机负荷陡变对AGC性能考核指标影响较大。针对汽轮机实际运行状况进行检查,发现了其存在的负荷陡变现象;在实际运行数据分析的基础上,从问题的机理层面出发,发现该现象是由两类不同原因导致的典型负荷陡变问题:一是信号测量的噪声问题,功率信号进行三选一滤波之后还是会出现陡变;二是调门连接硬件的故障问题,导致调门阀头处于不受控的状态,上下撺动而影响机组输出功率。并且,利用已有的有效实验测试对调门硬件故障进行定量定位,分析结果与实际吻合。最后,针对此故障提出了有效解决措施。这对保证大功率汽轮机的快速精准变负荷能力具有一定借鉴意义。