Dynamics of a plasma in a capillary discharge driven by a plasma focus operated in the mode of a plasma switch opening.

Abstract

A compact and simple type of current driver based on a plasma focus working in the mode of a plasma opening switch was used for excitation of a capillary discharge in Ar pressures in the range 0.1-0.5 Torr. A current of up to 50-60 kA with a rise time of about 200 ns was achieved in the capillary. The Ar plasma was compressed from an initial diameter of 5 mm to a diameter of 1 mm. The dynamics of compression have been studied using time-resolved VUV pin-hole diagnostics. Time-resolved VUV spectra show that the plasma consists mainly of the Ne- and F-like ions Ar IX and Ar X. A spectral line at 468.7 Å, which was identified as the transition in Ne-like Ar IX, has an anomalously high intensity compared with other 3-3 transitions of Ar IX.

MHD simulation of a fast hollow cathode capillary discharge

“…It is well known that a slower current pulse with a rise rate below 10 11 A s −1 does not result in the Ar plasma densities necessary for lasing, even if the required plasma temperature has been achieved. The situation seems to be similar for the current pulse with the rate dI/dt over the range 10 11 -10 12 A s −1 [12]. Thus, fast (dI/dt 10 12 A s −1 ) capillary discharge seems to be a good instrument for the investigation of lasing emission in Ar IX ions.…”

Transient electrical discharges in small devices

“…This is usually done by means of huge facilities such as the Sandia National Laboratory in the USA. 1,2 Intermediate devices have been used to produce vacuum ultraviolet ͑VUV͒ to soft x-ray radiation 3,4 the most well-known being soft x-ray lasing. 4,5 Interestingly, 10 12 J/m 3 can also be provided using small devices.…”

Analysis of High Resolution Ar IX Spectrum, Excited in Fast Capillary Discharge

“…The measured electric current through the capillary reaches 50^70 kA during the ¢rst 100 ns of discharge. The time-resolved X-ray pin-hole images [15] show, that the plasma in the capillary is quickly separated from the walls and is compressed to a uniform pinch about 1 mm in diameter, the measured pinch lifetime is about 100^200 ns. The electron temperature of the plasma is about 50^70 eV monotonously increasing with decreasing initial argon pressure.…”

“…The principal feature of this type of CD is a switch opening device which switches o¡ a main circuit and switches on a parallel circuit with capillary [13]. A plasma-erosion switch opening (PEOS) [14] is used in our source, which is an advanced version of the plasma source described in [15]. The scheme of the source is shown in Fig.…”