Gas-filled-capillary discharge experiment
We have studied high-current capillary discharge as a prospective XUV laser source since 1998. We have built two experimental devices CAPEX and CAPEX-U. On both these devices we have observed the very strong amplification of neon-like argon line at 46.9 nm, which corresponds to laser transition. Recently high resolved spectra were obtained with the help of McPherson spectrometer as well as a spherical Si/Sc multilayer mirror was used to focus laser pulses generated by a 46.9-nm capillary-discharge amplifier. The latest experimental results are presented in this paper.
Comparing of calculated and experimental results of CAPEX-U device
The CAPEX-U (CAPillary EXperiment-Upgrade) apparatus has been developed as an XUV source based on high-current capillary discharge. Our main motivation for building such new device was to create the XUV source with amplification of spontaneous emission at shorter wavelengths (below 20 nm), which have more practical applications (the soft X-ray source for lithography and microscopy). The final experimental setup of the new device is described and the preliminary experimental results of the assembled apparatus are presented, especially the capillary current signal, and the time development of the pulse-forming-line voltage. The comparison of these experimental results with calculated/predicted values is reported in this paper as well.
Atmospheric drag effects on the KOMPSAT-1 satellite during geomagnetic superstorms
We examine the atmospheric drag on the low earth-orbiting satellite, KOMPSAT-1 in a sun-synchronous orbit at ~685-km altitude starting in 1999, during a 3-month (October-December) period in 2003. This 3-month interval includes the October 29-30 and November 20 magnetic superstorms and weak to moderate storms. We observed that the daily KOMPSAT-1 drag acceleration transiently responses to transient storm-time disturbances. That is, there is an one-to-one correspondence between the KOMPSAT-1 drag accelerations and the storm events. We find that the drag acceleration correlates strongly with the level of geomagnetic disturbance. This indicates that the trajectory of KOMPSAT-1 is significantly perturbed during extremely disturbed intervals because of atmospheric density increase. The main contributor to the density increase is Joule heating associated with the geomagnetic activity rather than the solar EUV radiation, as reported by previous studies. We suggest that understanding how the upper atmosphere responses to the geomagnetic-associated heating is important to predict space weather impacts on low earth-orbiting satellites.