A new radar auroral backscatter experiment
In 1982 a new radar auroral backscatter system, SABRE (Sweden and Britain Radar Experiment), commenced operation in northern Europe. Observations with this ground-based system allow estimates to be made of the electric fields in the auroral E-region. As an electric field probe, the coherent radar technique is unique in that measurements are made over a large area (∼200,000 km2) with good spatial resolution (20 × 20 km2) and with a temporal resolution of typically 20 s. The system field of view covers an L-value range 4.3–5.8. This region in the magnetosphere–ionosphere system is now accessible for the first time for detailed electric field studies. We present here observations of two pulsation events.
Statistical average estimates of high latitude field-aligned currents from the STARE and SABRE coherent VHF radar systems
Abstract Two bistatic VHF radar systems, STARE and SABRE, have been employed to estimate ionospheric electric fields in the geomagnetic latitude range 61.1 – 69.3° (geographic latitude range 63.8 – 72.6°) over northern Scandinavia. 173 days of good backscatter from all four radars have been analysed during the period 1982 to 1986, from which the average ionospheric divergence electric field versus latitude and time is calculated. The average magnetic field-aligned currents are computed using an AE-dependent empirical model of the ionospheric conductance. Statistical Birkeland current estimates are presented for high and low values of the Kp and AE indices as well as positive and negative orientations of the IMF B z component. The results compare very favourably to other ground-based and satellite measurements.
Long Ceramic Beam Tubes for Accelerator Magnets
The ceramic beam tubes for the fast and abort kickers and the bucker and pinger magnets used at Fermilab must meet a number of exacting requirements. The tubes must be long and sufficiently straight so as not to limit magnet design. They must have wall strength capable of withstanding the atmospheric and mechanical forces encountered during construction and operation. Vacuum tight ceramic to stainless steel transitions must be of reasonable cost; they must also withstand high temperature processing and remain vacuum tight to the 10/sup -9/ Torr range. To remove the possibility of static charge buildup each tube must have a surface coating of indium oxide applied to the inner wall. This thin coating is difficult to achieve and requires the most careful attention to detail. The methods used at Fermilab to achieve these goals are presented in this paper.