4.18. SMITER-PFCFLUX benchmark ‘ELM case of ICRH optimized equilibrium on FWPs’

In this section the ELM heat loads are estimated with SMITER to the first wall panels 8-18 in the plasma configuration optimized for the ICRH coupling. The cases with the outboard midplane first separatrix shifted outwards by 4, 6, 8 and 10 cm with respect to the separatrix in the current QDT=10 H-mode reference equilibrium are present. This study was first done by Martin Kocan, reported in Heat loads to the ITER first-wall panels for the ICRH-optimized plasma equilibrium [DML5YK].

[DML5YK]Martin Kocan et al, ITER_IDM_DML5YK

In this report, baseline plasma equilibrium was taken. The heat loads to the outboard FWPs in the Baseline configuration are significantly below the FWP design limit, the cases presented in the report study the effects of shifting the plasma OMP separatrix towards the ICRH antenna and outboard FWPs. The cases were made of the outward shift of 4, 6, 8 and 10cm with respect to the Baseline plasma separatrix. The inter-ELM heat fluxes were neglected in these studiess, and only controlled intermittent-ELMs are included.

4.18.1. Input data

4.18.1.1. Equilibrium

The equilibrium used in this report is EQDSK-G geqPullTo8cmDsep8cm_00000_RDHR.eqdsk. This is the alternative equilibrium of 15MA plasma of DT scenario at burn. The outer mid-plane of the inner separatrix in this magnetic configuration has radial coordinate 8.3m (i.e. it is more out compared with the separatrix of the nominal magnetic configuration). The distance between inner and outer separatrices at the outer mid-plane is 7cm. This equilibrium has a 10 cm shift with respect to the Baseline configuration. It was used in other studies and moved back respectively for shifts of 4, 6 and 8 cm.

The radii of the first and second separatrices for different shifts are shown in the table below.

Equilibrium \(R_{sep1}[m]\) | \(R_{sep1}[m]\)
ICRH optimized, \(\delta_{OMP}=10cm\) 8.304 8.373
ICRH optimized, \(\delta_{OMP}=8cm\) 8.284 8.353
ICRH optimized, \(\delta_{OMP}=6cm\) 8.264 8.333
ICRH optimized, \(\delta_{OMP}=4cm\) 8.244 8.313
Baseline 8.205 8.299

4.18.1.2. Meshes

Target mesh includes FWPs ranging from 8 to 18 in poloidal direction. See Fig. 4.57.

../../_images/icrh_antenna_dml5yk_targetmesh.png

Fig. 4.57 Target mesh.

Shadow mesh includes all panels in toroidal direction (poloidal panels 8-18) as well as divertor PFCs. See Fig. 4.58.

../../_images/icrh_antenna_dml5yk_shadowmesh.png

Fig. 4.58 Shadow mesh.

4.18.2. Setting up the SMITER case

The study ITER_IDM_DML5YK_benchmark already contains target and shadow meshes and no additional action needs to be taken here. The meshes are

  • target_dml5yk
  • shadow_dml5yk

In these SMITER cases, custom power deposition profile is specified to include ELMs (unlike prevoius studies where the power deposition profile was exponential or double exponential).

4.18.2.1. GEOQ parameters

In the SALOME Object browser in SMITER section under “7_5_MA_SU_OUTBORD” case, one can right click on either target object (surf_be) or shadow object (Bm_mesh_surf_be) and select Edit CTL.

Under beqparameters one can observe following parameters

Parameter Value Description
beq_bdryopt 9 \(\psi_m=\psi_{ltr}\) Boundary based on nodes of geometry, outboard values are used for \(R_m,B_{pm}\) and \(B_m\)
beq_psiref -1.476 Reference PSI value at outer midplane
beq_fldspec 3 Use cylindrical coordinates
beq_rmove 0 Equilibrium displacement in radial direction

Note

Parameter beq_brdyopt is used to determine how to calculate value of flux at plasma boundary \(\psi_m\), and where to evaluate values of \(R_{m}\), \(B_{pm}\) (and \(B_{m}\)) used in power deposition formulae. The options to specify are either PSIREF, which will calculate the flux at plasma boundary based on limiter wall, given to SMITER, or any other float value given by the user.

Equilibrium is shifted back to different positions with beq_rmove.

4.18.2.2. HDSGEN parameters

Refer to general setting parameters for limiter cases for HDSGEN HNB study‣Setting up the SMITER case‣ Setting parameters for HDSGEN.

4.18.2.3. POWCAL parameters

Parameter Value Description
calculation_type global ‘global’ shadowing by fieldlines which may wrap around torus
shadow_control 1 Enable shadowing
power_loss 5e6 Power loss given in \(W\)
power_split 1 power split ion to electron direction.
decay_length 0.026 decay length in meters.
more_profiles .true. Set to .true. to activate edgprofparameters.

Note

The power loss and decay length are ignored later on in the computation, since we are specifying a custom profile.

Custom power deposition profile is defined in edgprofparameters. These parameters are

Parameter Value Description
coord_of_positions ‘radius’ Whether positions in distance or flux from SOL, the other option is thus ‘flux’
deposition_profile vals Array of deposition profile, values are separated by ‘,’
number_of_positions 100 Length of array of deposition profile
positions vals
Define profile as samples at these
positions
profile_formula ‘samples’ Set to .true. to activate edgprofparameters.

Note

Note that the maximum number of positions (number_of_position) is 100. If bigger number is given, SMITER wil throw an error.

The plot for ELM heat fluxes as a function of distance from the outer midplane separatrix is shown in Fig. 4.59.

../../_images/icrh_antenna_dml5yk_elmprofile.png

Fig. 4.59 Intermittent-ELM heat flux profile.

4.18.3. Results

The result for shift of \(10cm\) compared with PFCFLUX result is shown in Fig. 4.60.

../../_images/icrh_antenna_dml5yk_resultshift0.png

Fig. 4.60 Power deposition for equilibrium shift of \(10cm\) for SMITER (letf) and PFCFLUX (right).