XGC-S Input Parameters ====================== At the moment XGC-S has a separate input from the main tokamak XGC code, although some input variables are the same. Here we list the most important differences. It is recommended to start from a stellarator example in `XGC-Examples `_ when preparing an input file for relevant input variables. * XGC-S has an additional namelist ``&sml_param_stellarator`` that contains the following input variables: * ``sml_special_s`` - Simulation mode: 1 = general, 2 = flux-ave (default), 4 = trace. * ``sml_dir_file_s`` - (8 characters) directory name for equilibrium data (../equilibrium/********/ folder). * ``sml_infile_s`` - (8 characters) equilibrium files prefix. * ``sml_outfile_s`` - (6 characters) output files prefix. * ``sml_prf_file_s`` - (14 characters) profiles filename (../profile/**************/ file). * ``sml_step1_s`` - Initial time step of simulation. * ``sml_step2_s`` - Final time step of simulation. * ``sml_delta_s`` - Time step length in seconds. * ``sml_icon_vol_s`` - Node volume data (``*.vol`` files in ``sml_dir_file_s``): 0 = generate volume data, 1 = read volume data (default). For option 1 the ``*.vol`` files for the node volumes of all planes must already exist in the equilibrium data folder. * ``sml_icon_dlf_s`` - 0 = full-f, 1 = delta-f (default). Must use 1, full-f is not implemented. * ``sml_icon_bnd_s`` - Particle boundary condition at last closed flux-surface (not completed), must use 0 at present. * ``sml_icon_poi_s`` - Finite element Poisson solver: 0 = one dimensional field equation (default), 1 = Poisson solver (turbulence component), 2 = Poisson solver (average component), 3 = Poisson solver (turbulence + average component). * ``sml_icon_iso_s`` - Switch for mixed isotope plasma, not used at the moment. * ``sml_prep_poi_s`` - Iterative solver preparation (initial flux). Use 0. * ``sml_prep_poi_e`` - Iterative solver preparation (last flux). Use 0. * ``sml_icon_col_s`` - Collision scheme: 0 = no collisions. Collisions not implemented yet. * ``sml_icon_tokamak_s`` - Switch for equilibrium: 0 = stellarator simulation (default), 1 = tokamak wedge simulation. * ``sml_eqcef_s`` - Coefficient for equilibrium magnetic field. Normally use 1.0 (default). * ``sml_rdcef_s`` - Size of applied background radial electric field. Normally use 0.0 (default). * ``sml_diag_freq`` - Diagnostics time step output frequency. * In namelist ``&sml_param`` the input variables ``sml_dt``, ``sml_mstep``, ``sml_restart`` and ``sml_restart_write_period`` are ignored and replaced by the corresponding input in ``&sml_param_stellarator``. If restarting a simulation set ``sml_step1_s`` to the next step after ``sml_step2_s`` in the previous simulation. * In namelist ``&sml_param`` the input variables ``sml_node_file`` and ``sml_ele_file`` are ignored and replaced by the equilibrium input in ``&sml_param_stellarator``. * In namelist ``&sml_param`` the input variables ``sml_mode_select_on`` and ``sml_mode_select_n`` are ignored unless ``sml_icon_tokamak_s = 1`` because it is not possible to select a mode in a stellarator simulation. * In namelist ``&sml_param`` the input variables ``sml_nphi_total`` and ``sml_wedge_n`` must be consistent with the flag *-nv* for the number of toroidal cross-sections and the toroidal periodicity from the VMEC file (or torus wedge number for a tokamak) used when generating the equilibrium files with `VMEC2XGC2 `__ to ensure that the simulation is correct. Normally ``sml_wedge_n`` should be set to the toroidal periodicity and ``sml_nphi_total`` should be set to the value of *-nv* subtracted by 1 and then divided by 2, e.g. if using ``-nv 9`` then set ``sml_nphi_total = (9 - 1)/2 = 4`` when running XGC-S. However, it is also possible to use another combination of multiples of the *-nv* value and the periodicity, e.g. if using ``-nv 9`` for the mesh and the periodicity is 5 one can also run XGC-S with ``sml_nphi_total = 4*5 = 20`` and ``sml_wedge_n = 1`` instead of using ``sml_nphi_total = 4`` and ``sml_wedge_n = 5``. For a tokamak simulation, ``sml_icon_tokamak_s = 1``, these restrictions do not apply since all cross-sections are identical. * In namelist ``&sml_param`` the input variables ``sml_outpsi``, ``sml_bd_ext_delta3``, ``sml_bd_ext_delta4``, ``sml_bd_ext_delta3h`` and ``sml_bd_ext_delta4h`` must be consistent with the flag *-truncate* used when generating the equilibrium files with `VMEC2XGC2 `__. ``sml_outpsi`` minus each of ``sml_bd_ext_delta3``, ``sml_bd_ext_delta4``, ``sml_bd_ext_delta3h`` or ``sml_bd_ext_delta4h`` should be smaller than the value of *-truncate* to avoid errors in the Poisson solver. * In namelist ``&eq_param`` the input variables ``eq_filename``, ``eq_den_file``, ``eq_tempi_file`` and ``eq_tempe_file`` are ignored and replaced by the corresponding input in ``&sml_param_stellarator``. * Several namelist in main XGC are not included in XGC-S and many input variables in main XGC are either not included or ignored in XGC-S. Profiles -------- The input profiles specified in the file given by ``sml_prf_file_s`` has a different format than the main tokamak XGC code. The header line contains the number of equidistant intervals in normalized poloidal flux (label) that the profiles are specified on. This should typically be set to 1000. Then the 1st column is the label index and should run from 0 to 1001. The remaining 4 columns contain ion density in :math:`{\mathrm{m}}^{-3}`, ion density gradient, ion temperature in :math:`{\mathrm{eV}}` and ion temperature gradient for the flux-surfaces. The gradients are with respect to the normalized poloidal flux :math:`\psi/\psi_a`. Note that the label index 1000 corresponds to the last closed flux-surface :math:`\psi/\psi_a = 1.0`, i.e. label 1001 is one radial grid point outside the last flux-surface. Label 0 corresponds to the axis :math:`\psi/\psi_a = 0.0`. .. code-block:: bash 1000 0 5.624773740559e+19 0.000000000000e+00 7.118281580739e+02 0.000000000000e+00 1 5.624773740559e+19 1.346323821783e+17 7.118281580739e+02 5.111429221637e+00 2 5.624784215859e+19 7.466412884047e+16 7.118321351095e+02 2.834688018309e+00 3 5.624788688332e+19 3.953354175467e+16 7.118338331249e+02 1.500927420624e+00 4 5.624792130482e+19 3.173288427232e+16 7.118351399692e+02 1.204768440686e+00 [...] i n_i d(n_i)/d(psi/psi_a) T_i d(T_i)/d(psi/psi_a) [...] 999 4.460481422239e+19 3.640960420413e+14 3.549810715080e+02 8.692819217686e-03 1000 4.460481459376e+19 3.778929072538e+14 3.549810803744e+02 9.022220619954e-03 1001 4.460481459376e+19 0.000000000000e+00 3.549810803744e+02 0.000000000000e+00 *Example of a profiles file for XGC-S.* .. toctree:: :maxdepth: 1