This page describes the instrument and the data products now available from that instrument.
The electron experiment on UKS was built by Space Plasmas group at the Rutherford Appleton Laboratory. This instrument used twin electrostatic analysers to measure the electron distribution over the energy range from 6 eV to 25 keV. It could be commanded to operate in a variety of modes, e.g. (i) a full energy scan from 12 eV to 25 keV in one second; (ii) scans from 12 eV to 25 keV and from 12 to 680 eV in alternate seconds. Full details of the instrument are available in the following paper:
H. M. Shah, D.S. Hall and C.P. Chaloner, "The electron experiment on AMPTE UKS", IEEE Transactions on Geoscience and Remote Sensing, GE-23(3), May 1985, 293-300.
For a more detailed discussion of the AMPTE-UKS electron measurements and their conversion to physical quantities, click here.
RAL has generated a number of standard electron data products for inclusion in the AMPTE-UKS database. These are mainly moments including:
These data products, together with many other AMPTE products, are available via the UK Coordinated Data Handling Facility for STP. Users of these electron products should read the electron data caveats, which describe known aspects or problems with the AMPTE UKS electron data. A short note describing the principles underlying the moments calculation is available as a Postscript file.
Note that the parallel and perpendicular temperature (T) may be derived from the corresponding pressure terms (P) using the formula:
T (eV) = 9.375 x 10+18 * P (pascals) / Ne (m-3)
where Ne is the number density. These temperatures are expressed as energy and are equal to 3 k Tk /2 where Tk is expressed in kelvins and k is Boltzmann's constant. To estimate the mean isotropic temperature we note that the parallel temperature has only one degree of freedom whereas the perpendicular temperature has two. Thus:
T_mean = ( T_parallel + 2.0 * T_perpendicular) / 3.0
A variety of other electron data products can be generated on request, e.g. for use in collaborative projects. These products include:
For an example see a colour Postscript file showing intensities parallel, perpendicular and anti-parallel to the magnetic field during a magnetopause crossing on 11 November 1984.
To discuss access to these other UKS electron data products please contact Mike Hapgood at RAL (Email: M.Hapgood@rl.ac.uk).
The raw data from the UKS electron instrument are securely archived at RAL. They are currently held in a Unix file structure within the large central filestore operated by RAL's Department for Computing and Information. This allows the whole dataset (1.6 gigabytes) to be NFS-mounted on the Unix workstation which hosts our software for processing these software.
The master copy of the dataset had previously been held on two large (twelve-inch) optical discs and before that on a number of half-inch magnetic tapes. The latter were the original archive generated at the end of UKS operations. The data have been migrated to new media as the older media became obsolete. This has resulted in a gradual reduction of the number of physical elements required to store the data and an increase in the ease of access to the archive. In previous schemes, users could access only a subset of the archive that was copied into a buffer area on local magnetic disc. Thus, before users could access data not in the buffer, they had to request an operator to copy raw data from the archive into the buffer. In the latest scheme, the whole archive can be read directly by any authorised user (though, for efficient software operation, they should copy the data of interest on to a local magnetic disc).