Plasma boundary identification is a basic task for studies on equilibrium and confinement in a divertor tokamak. With the progress on the experiments after engineering experiments, the boundary identification becomes an important issue for HL-2A. In order to satisfy the requirements of preciseness, simplified measurements and quickness, the filament current method instead of solving the equilibrium equations is used to identify plasma boundary on HL-2A. The involved principle, mathematics and the progresses, which have been made with this method, are given.
为了研究HL-2A等离子体偏滤器位形,研制了等离子体形状实时显示系统.采用固定位置电流丝和有限电流元的方法编写了CF编码.采用32道同时刻采集器UA301采集等离子体周围的磁场信息,使用P43GHz E CPU组装的兼容计算机处理数据.这个系统每4ms采集一次数据并存盘,每16ms重画一次等离子体边界.放电结束后可以详细地计算等离子体边界及其磁场以及由此导出的等离子体参数.
Because the last closed flux-surface （LCFS） finally determines the shape of plasma cross-section, and the shaping of plasma is a key issue directly related with lots of the hot subjects of an advanced tokamak（AT） and of a reactor, e. g., the control on the current density, equilibrium, scrapeoff layer（SOL）, aspects of edge particle and energy, high plasma kinetic energy, and of course, the MHD instability suppression, the further studies on the LCFS related subjects, e. g., its determination, flux loss, etc., are still tokamak research. It equilibrium, poloidal needed for present is also important to get precise LCFS-related equilibrium or configuration properties for the controls on an AT and for the understandings on the underlying basic physical issues in a discharge.
LI Qiang MAO Suying LUO Cuiwen PAN Li ZHANG Jinhua YANG Qingwei SONG Xianming
The Ethernet and field-bus communications are used in the machine control system （MCS） of HL-2A. The control net, with a programmable logic controller （PLC） as its logic control master, an engineering control management station as its net server, and a timing control PC connected to a number of terminals, flexibly and freely transfers information among the nodes on it with the Ethernet transmission techniques. The PLC masters the field bus, which carries small pieces of information between PLC and the field sites reliably and quickly. The control net is connected into the data net, where Internet access and sharing of more experimental data are enabled. The communication in the MCS guarantees the digitalization, automation and centralization. Also provided are a satisfactory degree of safety, reliability, stability, expandability and flexibility for maintenance.
