Mesh

There are two output files containing mesh parameters (the 5D mesh consists of a 3D unstructured triangular mesh in configuration space and a 2D structured rectangular grid in velocity space): xgc.f0.mesh.bp and xgc.mesh.bp.

Remarks

These files contain quantities that can be useful to calculate various averages.

# flux surfaces here includes the scrape-off layer, i.e. the open field-line region.

xgc.f0.mesh.bp
Printed when: sml_f0_grid=.true..   Output frequency: once at start/restart.

Output	Dimension	Units	Description
f0_T_ev	\(N_{\mathrm{species}}~\times\) # 3D mesh nodes	\(\mathrm{eV}\)	Temperature at start in all configuration space vertices for electrons (0) and ions (1).
f0_den	# 3D mesh nodes	\({\mathrm{m}}^{-3}\)	Density at start in all configuration space vertices. Is n_e = n_i assumed?
f0_dsmu	Scalar	\(v_{Ts} = \sqrt{\frac{T_s}{m_s}}\)	\(\Delta v_{\perp}\) in the 2D velocity grid of species \(s\).
f0_dvp	Scalar	\(v_{Ts} = \sqrt{\frac{T_s}{m_s}}\)	\(\Delta v_{\|}\) in the 2D velocity grid of species \(s\).
f0_grid_vol_vonly	\(N_{\mathrm{species}}~\times\) # 3D mesh nodes	Units	Prefactor for calculating velocity space moments. \(= \left( T_s/\sqrt{2 \pi} \right) \times \) \(\times\) dvp_n. Note that mu_vol and vp_vol are different and not included. In calculating density moment, for example: \(n_s(k)=\) f0_grid_vol_vonly(k) \(\sum_{i,j}\) mu_vol(i) vp_vol(j) f(i,j,k)
f0_nmu	Scalar	Positive integer	Number of grid points in \(v_{\perp}\) in the 2D velocity grid is f0_nmu + 1. Same as input parameter f0_nmu.
f0_nvp	Scalar	Positive integer	Number of grid points in \(v_{\|}\) in the 2D velocity grid is 2 \(\times\) f0_nvp + 1. Same as input parameter f0_nvp.
f0_smu_max	Scalar	\(v_{Ts} = \sqrt{\frac{T_s}{m_s}}\)	Maximum \(v_{\perp}\) in the 2D velocity grid (minimum is \(0\)). Same as input parameter f0_smu_max.
f0_vp_max	Scalar	\(v_{Ts} = \sqrt{\frac{T_s}{m_s}}\)	Maximum/minimum \(v_{\|}\) (minimum with minus sign) in the 2D velocity grid. Same as input parameter f0_vp_max.
gradpsi	# 3D mesh nodes \(\times\) 2	Units	Description
inode1m1	Scalar	Units	Description
n_n	Scalar	Positive integer	Number of 3D mesh nodes.
nb_curl_nb	# 3D mesh nodes	Units	Description
ndata	Scalar	Positive integer	Description
nsp	Scalar	Positive integer	Number of kinetic species.
v_curv	# 3D mesh nodes \(\times\) 3	Units	Description
v_gradb	# 3D mesh nodes \(\times\) 3	Units	Description

xgc.mesh.bp
Printed when: always.   Output frequency: once at start/restart.

Output	Dimension	Units	Description
PEST_angle	# poloidal planes * \(\times\) # planar mesh nodes	Radians	PEST coordinate on the mesh nodes (only written for stellarator simulations).
VMEC_angle	# poloidal planes * \(\times\) # planar mesh nodes	Radians	VMEC coordinate on the mesh nodes (only written for stellarator simulations).
delta_phi	Scalar	Radians	Toroidal angle increment for each poloidal plane.
epsilon	# flux surfaces	Normalized	Inverse aspect ratio rmin/rmaj for the flux surface.
ff_1dp_p	2 \(\times\) # 3D mesh nodes \(\times\) 3	Units	Description
ff_hdp_p	2 \(\times\) # 3D mesh nodes \(\times\) 3	Units	Description
grid_nwall	Scalar	Positive integer	Number of nodes that make up the boundary of the domain (and represent the wall).
grid_wall_nodes	nwall	Positive integer	Node index for each wall node. Currently not “ordered”, but in the order specified in .node file.
m_max_surf	# flux surfaces	Positive integer	Maximum resolvable poloidal mode number on each flux surface. Defined by field-following alignment when generating the mesh.
mapping	# 3D mesh triangles \(\times\) 3 \(\times\) 2	m	Defines coordinates of triangle vertices.
n_geo	Scalar	Positive integer	Number of flux surfaces. Same as nsurf.
n_n	Scalar	Positive integer	Number of 2D mesh nodes.
n_t	Scalar	Positive integer	Number of 2D mesh triangles.
nd_connect_list	# poloidal planes * \(\times\) # 3D mesh triangles \(\times\) 3	Integer	Defines triangular mesh on each poloidal plane (similar to, but indexed differently from .ele file). First index is triangle index and the second index is over the three nodes that make up the triangle’s vertices. These are labelled by the index of the mesh node (from .node file). Index of nodes counts starting from zero.
nextnode	# 3D mesh nodes	Units	Description
node_vol	# 3D mesh nodes	\(\mathrm{m}^{3}\)	Spatial volume of the 3D mesh node. Volume of whole torus is wedge_n \(\times\) n_phi_tot \(\times \sum_k\) node_vol(k).
node_vol_ff0	# 3D mesh nodes	Units	Description
node_vol_ff0_l	# 3D mesh nodes	Units	Description
node_vol_ff0_r	# 3D mesh nodes	Units	Description
node_vol_ff1	# 3D mesh nodes	Units	Description
node_vol_ff1_l	# 3D mesh nodes	Units	Description
node_vol_ff1_r	# 3D mesh nodes	Units	Description
node_vol_nearest	# 3D mesh nodes	\(\mathrm{m}^{3}\)	Description
nphi	Scalar	Positive integer	Number of poloidal planes \(N_{\mathrm{planes}}\) (only written for stellarator simulations).
nsurf	Scalar	Positive integer	Number of flux surfaces.
one_per_dx	2 \(\times\) # 3D mesh nodes	Units	Description
psi	# 3D mesh nodes	Weber/rad	Toroidal magnetic flux for the flux surface that the node is on.
psi_surf	# flux surfaces	Weber/rad	Toroidal magnetic flux for the flux surface.
qsafety	# flux surfaces	Normalized	Safety factor \(q\) for the flux surface.
region	# 2D mesh nodes	Integer value	Region number for each node. 1 for core, 2 for SOL, etc.
rmaj	# flux surfaces	m	Major radius of flux surface.
rmin	# flux surfaces	m	Minor radius of flux surface
rz	# poloidal planes * \(\times\) # 3D mesh nodes \(\times\) 2	Meters	Defines the spatial location in the poloidal plane for each mesh node. First index defines the node. Second index is the \((R,Z)\) coordinate of the node.
surf_arc_len	# flux surfaces	m	Poloidal arc-length of the complete flux surface.
surf_idx	# flux surfaces \(\times\) surf_maxlen	Positive integer	Node index for each node on a flux surface. First index is flux surface label and second index is the node on the flux surface. Nodes counted from 1. Filled with zeros beyond surf_len.
surf_len	# flux surfaces	Positive integer	Number of nodes in each flux surface.
surf_maxlen	Scalar	Positive integer	The maximum number of nodes on any flux surface. Used for indexing surf_idx.
theta	# 3D mesh nodes	Normalized	Poloidal coordinate.
tr_area	# 3D mesh triangles	Units	Triangle areas.
trapped	# flux surfaces	Normalized	Trapped particle fraction for flux surface.
wedge_angle	Scalar	Radians	Torus wedge angle or toroidal periodicity.
wedge_n	Scalar	Positive integer	Torus wedge number or toroidal periodicity (only written for stellarator simulations).

* Dimension only for stellarator simulations.