2.8. TCV Benchmark Case¶
2.8.1. Validation of the 2D model based heat flux approach on TCV tokamak¶
SMITER-GUI development started with the intent of to be used only for the ITER tokamak analysis but is currently also capable of performing analysis for any other tokamak device that varies from the ITER tokamak (no active cooling like ITER, size, …). Following that statement, the goal of this tutorial subsection is to demonstrate this SMITER-GUI capability of analysis of tokamak devices other than ITER, in this case, the TCV tokamak.
Experimental heat flux diagnostics on graphite tiles in the vacuum vessel of TCV tokamak was measured with the use of an infrared camera. The intent of TCV Infrared thermography was to capture heat flux distribution on the tiles and parallel heat flux profile in the scrape-off layer region. First, temperature images were produced as the output of the infrared camera. Then, in order to get the power deposition, the temperature cylindrical coordinates (\(T(R,\Psi,Z)\)) via Theodor code were mapped to magnetic coordinates (\(q_{dep}(dR,\alpha)\)). The power deposition on magnetic coordinates was then modelled as parallel heat flux (\(q_{||}(dR)\)).
Our region of interest is shown in Fig. 2.23.
Fig. 2.23 Region of interest, observed with an infrared camera of the first wall panels 3, 4 and 5, is marked with green color.
2.8.2. Input Parameters based on Experimental Data¶
The radial heat flux profile in SOL region is presented in Fig. 2.24. The required parameters for double exponential formula, \(L_{far}, R_{near} and L_{near}\), were extracted from the radial profile of heat flux in SOL region.
Fig. 2.24 Experimental data (red squares) for radial heat flux in SOL.
Input parameters for double exponential formula are defined as
- Power loss \(P_{loss}\) = 126 kW
- Decay length near \(\lambda\) = 2.8 mm
- Decay length \(\lambda\) = 31.2 mm
- Near-SOL parallel relative reference flux \(R_{near}\) = 3.5
2.8.3. Preparing the CAD model and meshing¶
THe TCV operators supplied parametric curve in the .mat (Matlab) format that
resembles the shape of the first wall panel 4. The first step is to create
a surface from this curve that matches the panel in TCV tokamak. First,
we have to import this curve into GEOM module and then extract it in the
\(z\) - direction in order to get the full surface, that can be
used as base CAD model for creating shadow and target. To do that we
use python function, that loads all the points in the python script.
scio.loadmat()
We then use GEOM library to create the desired surface (Tutorials
on how to program CAD models with GEOM library are shown in section
Using GEOM module). The height of the panel is 200 mm. See
Fig. 2.25.
Fig. 2.25 Left: Curve of the shape of TCV panel. Right: CAD model of panel.
After the model is created we can move to SMESH module and mesh the existing panels (Tutorials on how to use SMESH model and mesh the CAD models are shown in section Using SMESH module). Since our region of interest are panels 3, 4 and 5, we can just copy mesh of FWP 4 two times and translate one copy for +201 mm in z-direction to get FWP 5 and the other copy for -201 mm in the z-direction to get FWP 3. Then we can create the compound mesh from those three models to get the full target. Our shadow consists of one neighbouring segment on the left and right side. So we can just create two copies of our target mesh and then rotate one copy for +11.25° around z-axis and the other copy for -11.25°. Both target and shadow meshes are presented in Fig. 2.26.
Fig. 2.26 Left: Shadow mesh. Right: Target mesh.
2.8.4. Study Parameters¶
Main parameters for the powcal control files are defined as
- power_loss \(P_{loss}\) = 126 kW
- decay_length_near \(\lambda\) = 2.8 mm
- decay_length \(\lambda\) = 31.2 mm
- ratio_of_q_parallel_near \(R_{near}\) = 3.5
- profile_formula = ‘expdouble’
