Lightning trip-out risk evaluation of a 220kV transmission line in Shiyan
The lightning trip-out accidents of Shiyan transmission lines occur frequently. The lightning parameters, lightning faults and geography of 220kV shi-xuan transmission line have been collected. The lightning striking simulation model has been built by using electromagnetic transient calculation software ATP-EMTP and multi-wave impedance model. The lightning withstanding level of tower and the lightning trip-out rate have been calculated. The actual operation of the transmission line has been considered in order to evaluate the risk of lightning trip-out. The results can provide guidance for the lightning protection of transmission linewhich locates in mountains.
Novel approach for determining spots of critical lightning performance along transmission lines
A novel approach is proposed for determining critical spots along transmission lines, concerning lightning performance. It takes into account two localized factors: stroke density and response of line structures to lightning currents. The methodology employs data supplied by lightning location systems and also information about line parameters in order to rank, by means of a severity index, the specific towers along line, which deserve protective actions. The procedure was applied to a real 230 kV line. The results, in terms of first ranked towers, were compared to the history of line outages, as indicated by a fault locator. The results were in very good agreement. This denotes the potential of the proposed approach for general application.
Magnetic plasma confinement for laser ion source.
A laser ion source (LIS) can easily provide a high current beam. However, it has been difficult to obtain a longer beam pulse while keeping a high current. On occasion, longer beam pulses are required by certain applications. For example, more than 10 micros of beam pulse is required for injecting highly charged beams to a large sized synchrotron. To extend beam pulse width, a solenoid field was applied at the drift space of the LIS at Brookhaven National Laboratory. The solenoid field suppressed the diverging angle of the expanding plasma and the beam pulse was widened. Also, it was observed that the plasma state was conserved after passing through a few hundred gauss of the 480 mm length solenoid field.