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Rob Veenhof,
NIKHEF (Amsterdam, the Netherlands)
Version 6.25 features an interface for the new Maxwell field map formats.
This release also contains potentials for space charge calculations in
the vicinity of wires.
CELL section:
The interface for Maxwell 3D files computes the dielectric constant by
comparing E and D and, by default, identifies the drift region as the
medium with the lowest dielectric constant.
Until recently, this failed since epsilon was computed as E/D rather
than D/E.
This has now been corrected.
Dielectric constants are now expressed as multiples of epsilon_0.
Commands have been added that perform a save and retrieve of
binary field maps.
These commands are called SAVE-FIELD-MAP and
READ-FIELD-MAP.
Binary field maps are about 10 times smaller than Maxwell field maps,
and reading them is more than 10 times faster, but binary field maps
are not portable between computer systems.
An interface has been added for version 4.0 of the Ansoft program
"Maxwell 3D Field Simulator".
This is at CERN the successor to version 1.1 of another Ansoft program,
"Maxwell 3D Parameter Extractor".
MAGNETIC-FIELD section:
No changes.
OPTIMISATION section:
Potentials for point charges near a wire, point charges near a tube wall
and point charges between a wire and a tube wall have been computed by
Thomas Heubrandtner and Bernhard Schnizer, Graz.
Most of these potentials have been programmed and are to be introduced in
versions coming up over the coming months.
FIELD section:
Options have been added to PLOT GRAPH that give control
over the vertical scale of the graph, over the number of points and
over the curve to be used for making the graph.
Contours close to conductors and dielectric media were so far not
always drawn.
The contour routines have been modified to considerably reduce
the region over which this occurs.
GAS section:
Heed initialisation data is now stored in compact format gas files,
and the GET procedure automatically initialises Heed.
The procedure TRANSVERSE_DIFFUSION so far returned the
longitudinal diffusion while LONGITUDINAL_DIFFUSION
returned the transverse diffusion (Hervé Borel).
This has been corrected.
DRIFT section:
Runge-Kutta-Fehlberg drift line integration occasionally abandoned
drift lines because of large kink angles in the (x,y) plane while
the true kink, including the z-component, was much smaller.
This has been corrected and drift lines should less frequently
be abandoned now.
Large kinks are rare in smooth fields, the most common reason for
sharp bends being an attempt to cross a saddle point.
Field maps generated by finite element programs however sometimes
have discontinuities in the electric field between neighbouring
tetrahedrons.
To deal with such situations, an option CHECK-KINKS has
been added which can be used to suppress the check for sharp bends.
Termination of drift lines for fields derived from a map has been
improved.
Facilities are being added for drifting particles in vacuum.
SIGNAL section:
No changes.
Graphics:
Use of diacritics and ligatures in HIGZ compilations has been
simplified - some of them can be obtained via the SGML entity names.
For instance, é becomes é.
Histograms, Matrices, Formulae and Calls:
A longstanding problem, the incomplete garbage collect of temporary
matrices generated when indexing matrices, should be fixed now.
Moreover, indexed assignments in loops are now pre-processed
rather than interpreted.
This should lead to appreciable CPU time savings.
With a view to the increased use of procedures, most procedures
now verify that they are called in an appropriate environment.
In general this means that e.g. drift procedures should not be
called before both a cell and a gas section have been completed.
The ELECTRIC_FIELD, ELECTRIC_FIELD_3 and
SIGNAL_FIELD procedures now accept Matrix type arguments.
The z-components of the weighting field has been added to the
argument list of SIGNAL_FIELD.
Datasets and input / output:
No changes.
Global options:
No changes.
Compilation:
No changes.
Documentation
Currently, the most accurate
description
of the program can be found in the
on-line help.
The printed manual is not available at the moment.
A set of
examples
can be found on
WWW.
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