Analysis of ICRH Antennas by Topica code

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Analysis of ICRH Antennas by Topica code

• Vito Lancellotti, Daniele Milanesio, Riccardo
  Maggiora, Giuseppe Vecchi

MIT, February 15th, 2005
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Topica 3 architecture
Antenna drawing
Pre-processing module
Spatial domain
Post-processing module
Spectral domain
Admittance matrix and currents visualization
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Matrix form or the formulation
where
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Antenna drawing

• Draw the antenna with Gid graphic tool
• Select problem type
• Assign materials to the whole structure
• Select feeding (voltage gap vs. coax cable)
• Identify ports according to feeding
• Mesh the antenna
• Export the mesh of the antenna

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Gid background
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About normals
Normals to surfaces with magnetic current
distribution (aperture and coax cable) MUST be
directed toward the antenna cavity
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Select problem type
In order to be visible, the Antenna.gid folder
should be copied in the problemtypes folder
inside Gid working directory
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First materials selection
Color every surface with antenna or aperture
material
ANTENNA all surfaces with electric current
distribution
APERTURE all surfaces with both electric and
magnetic current distributions (i.e. the aperture
of the antenna cavity)
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Which feeding?
According to feeding you select, there are two
different sequences of operations you need to
complete to finish the antenna design
VOLTAGE GAP mesh the structure and assign the
materials port and ground to single triangles
COAX CABLE assign port material to surfaces
corresponding to the vacuum circular corona of
the cables and then mesh the structure
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Voltage gap
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Voltage gap - Mesh
Mesh can be structured only for some surfaces
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Voltage gap - Mesh
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Voltage gap Port selection
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Voltage gap Port selection
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Voltage gap Ground
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What is ground material?
In case of voltage gap feeding, the ground
material is used to identify every T- triangle
belonging to a RWG function that is part of a port
Every T triangle is instead colored with the
correspondent port material
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Coax cable Port selection
Assign ports before meshing the structure
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Coax cable - Mesh
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How to export mesh
Save the file as Name_of_antenna.txt
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Pre-processing module

• Copy the exported mesh file into the working
  directory
• Set all parameters inside triangoli.inp input
  file
• Run ReaderM2.exe file on your personal computer

You should obtain a Name_of_structure.mix.msh
file containing the RWG function mesh of the
antenna, i.e. the input file for modules
computing interactions both in the antenna and in
the plasma region
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Spatial domain
Once the pre-processing module has produced the
right geometry file, it is possible to compute
the interaction between functions with electric
and magnetic current distributions
In detail, you should run two modules
ASTERIONE computes the electric-electric and
magnetic-magnetic interaction between RWG
functions
ZEM15 computes the electric-magnetic
interaction between RWG functions and
automatically detects ports
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Spectral domain

• Set FELICE code parameters according to each
  plasma case
• Run FELICE code with arbitrary kt and phi for a
  preliminary analysis of hot plasma
  characteristics
• On visualizing Zp_11, obtain the value of kt
  where to stop adopting the hot plasma spectral
  Greens function

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Hot-cold transition
It is possible to identify the perfect point of
transition between hot plasma model and cold
plasma model the kt where the real part of
bramb11 reaches its maximum is an optimum choice
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Spectral domain

• Set parameters inside df.std input file
• Run topstc40.exe first to build the grid of kt
  and phi points whereon the hot plasma Greens
  function is actually required for calculations
• Run again FELICE code on this grid
• Run topstc40.exe again to compute the plasma
  contribution Gp

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Post-processing module

• Run Post4.exe (be sure that you already have
  all interaction matrices from previous modules!)

You obtain the admittance matrix of the structure
and, if the current parameter is set to true,
also the distribution of current for every RWG
function
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Current visualization
Its possible to save the electric current
distribution on the entire antenna and the
magnetic current distribution on the interface
between the vacuum region ad the plasma region
Starting from the magnetic current distribution
on the aperture of the cavity, you can easily
obtain the electric field
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Current visualization