2. Normalization

2.1. Reference units

We denote the reference values of physical quantities as follows.

  • Reference magnetic field strength \(B_\mathrm{ref}\) ( \(=B_a\) magnetic field strength at the magnetic axis)

  • Reference length \(L_\mathrm{ref}\) ( \(=R_a\) major radius at the magnetic axis)

  • Reference density \(n_\mathrm{ref}\) ( \(=n_e(\rho_0)\) electron density at the center of flux-tube domain)

  • Reference temperature \(T_\mathrm{ref}\) ( \(=T_i(\rho_0)\) main ion temperature at the center of flux-tube domain)

  • Reference mass \(m_\mathrm{ref}\) ( \(=m_\mathrm{p}\) the proton mass)

  • Reference electric charge \(e_\mathrm{ref}\) ( \(=e\) elementary charge)

We also define the following notations \(v_\mathrm{ref} = \sqrt{T_\mathrm{ref} / m_\mathrm{ref}}\) , \(\rho_\mathrm{ref} = m_\mathrm{ref} v_\mathrm{ref} / (e_\mathrm{ref} B_\mathrm{ref})\) , \(\delta_\mathrm{ref} = \rho_\mathrm{ref} / L_\mathrm{ref}\) . For single-species simulations with adiabatic electron/ion models, see Appendix Adiabatic electron/ion model for nprocs=1 .

2.2. Normalized equations

We represent a dimensionless quantity by an overline, \(\bar f\) , in this section.

The coordinates, variables, operators are normalized as

(2.1) \[\begin{split}&t = \frac{L_\mathrm{ref}}{v_\mathrm{ref}} \bar{t},~~ x=\rho_\mathrm{ref} \bar{x},~~ k_x = \frac{1}{\rho_\mathrm{ref}} \bar{k}_x,~~ y=\rho_\mathrm{ref} \bar{y},~~ k_y = \frac{1}{\rho_\mathrm{ref}} \bar{k}_y,~~ z = \bar{z}, \nonumber \\ &v_\parallel= v_\mathrm{ts} \bar{v}_\parallel = v_\mathrm{ref} \sqrt{\frac{\bar{T}_\mathrm{s}}{\bar{m}_\mathrm{s}}} \bar{v}_\parallel,~~ \mu = \frac{T_\mathrm{s}}{B_\mathrm{ref}} \bar{\mu} = \frac{T_\mathrm{ref}}{B_\mathrm{ref}} T_\mathrm{s} \bar{\mu}, \nonumber \\ &\tilde{f}_{\mathrm{s}\bm{k}} = \delta_\mathrm{ref} \frac{n_\mathrm{s}}{v_\mathrm{ts}^3} \bar{f}_{\mathrm{s}\bm{k}},~~ \tilde{\phi}_{\bm{k}} = \delta_\mathrm{ref} \frac{T_\mathrm{ref}}{e_\mathrm{ref}}\bar{\phi}_{\bm{k}},~~ \tilde{A}_{\parallel\bm{k}} = \delta_\mathrm{ref} \rho_\mathrm{ref} B_\mathrm{ref}\bar{A}_{\parallel\bm{k}}, \nonumber \\ &n_\mathrm{s} = n_\mathrm{ref} \bar{n}_\mathrm{s},~~ T_\mathrm{s} = T_\mathrm{ref} \bar{T}_\mathrm{s},~~ m_\mathrm{s} = m_\mathrm{ref} \bar{m}_\mathrm{s},~~ e_\mathrm{s} = e_\mathrm{ref} \bar{e}_\mathrm{s}, \nonumber \\ &\nabla_\parallel = \frac{1}{L_\mathrm{ref}} \bar{\nabla}_\parallel,~~ \bm{v}_{\mathrm{sG}} = \delta_\mathrm{ref} v_\mathrm{ref} \bar{\bm{v}}_{\mathrm{sG}},~~ \bm{v}_{\mathrm{sC}} = \delta_\mathrm{ref} v_\mathrm{ref} \bar{\bm{v}}_{\mathrm{sC}},~~ \bm{v}_{\mathrm{s}*} = \delta_\mathrm{ref} v_\mathrm{ref} \bar{\bm{v}}_{\mathrm{s}*}, \nonumber \\ &F_\mathrm{sM} = \frac{n_\mathrm{s}}{v_\mathrm{ts}^3} \bar{F}_\mathrm{sM},~~ J_{0\mathrm{s}\bm{k}} = \bar{J}_{0\mathrm{s}\bm{k}},~~ \Gamma_{0\mathrm{s}\bm{k}} = \bar{\Gamma}_{0\mathrm{s}\bm{k}},~~ \nonumber \\ &K_x = \frac{1}{L_\mathrm{ref}} \bar{K}_x,~~ K_y = \frac{1}{L_\mathrm{ref}} \bar{K}_y, L_{n\mathrm{s}} = L_\mathrm{ref} \bar{L}_{n\mathrm{s}},~~ L_{T\mathrm{s}} = L_\mathrm{ref} \bar{L}_{T\mathrm{s}},~~ \nonumber \\ &\frac{dP}{dx} = \frac{n_\mathrm{ref}T_\mathrm{ref}}{L_\mathrm{ref}} \frac{d\bar{P}}{d\bar{x}},~~ c_b = B_\mathrm{ref} \bar{c}_b,~~ B = B_\mathrm{ref} \bar{B}, \nonumber \\ &\frac{\partial \ln B}{\partial x} = \frac{1}{L_\mathrm{ref}} \frac{\partial \ln \bar{B}}{\partial \bar{x}},~~ \frac{\partial \ln B}{\partial y} = \frac{1}{L_\mathrm{ref}} \frac{\partial \ln \bar{B}}{\partial \bar{y}},~~ \frac{\partial \ln B}{\partial z} = \frac{\partial \ln \bar{B}}{\partial \bar{z}},~~ \nonumber \\ &g^{xx} = \bar{g}^{xx},~~ g^{xy} = \bar{g}^{xy}, g^{xz} = \frac{1}{L_\mathrm{ref}} \bar{g}^{xz},~~ g^{yy} = \bar{g}^{yy},~~ \nonumber \\ &g^{yz} = \frac{1}{L_\mathrm{ref}} \bar{g}^{yz},~~ g^{zz} = \frac{1}{L_\mathrm{ref}^2} \bar{g}^{zz},~~ \sqrt{g} = L_\mathrm{ref} \sqrt{\bar{g}},~~ \nu = \frac{v_\mathrm{ref}}{L_\mathrm{ref}} \bar{\nu}, \nonumber \\ &N_{\mathrm{s}\bm{k}} = \frac{v_\mathrm{ref}}{L_\mathrm{ref}}\delta_\mathrm{ref} \frac{n_\mathrm{s}}{v_\mathrm{ts}^3} \bar{N}_{\mathrm{s}\bm{k}},~~ C_{\mathrm{s}\bm{k}} = \frac{v_\mathrm{ref}}{L_\mathrm{ref}}\delta_\mathrm{ref} \frac{n_\mathrm{s}}{v_\mathrm{ts}^3} \bar{C}_{\mathrm{s}\bm{k}}.\end{split}\]

Then, the normalized equations are

(2.2) \[\begin{split} &\frac{\partial \bar{f}_{\mathrm{s}\bm{k}}}{\partial \bar{t}} + \left( \sqrt{\frac{\bar{T}_\mathrm{s}}{\bar{m}_\mathrm{s}}} \bar{v}_\parallel \bar{\nabla}_\parallel + i \bar{\bm{k}} \cdot \bar{\bm{v}}_\mathrm{sG} + i \bar{\bm{k}} \cdot \bar{\bm{v}}_\mathrm{sC} \right) \left( \bar{f}_{\mathrm{s}\bm{k}} + \frac{\bar{e}_\mathrm{s} \bar{F}_\mathrm{sM}}{\bar{T}_\mathrm{s}} \bar{J}_{0\mathrm{s}\bm{k}} \bar{\phi}_{\bm{k}} \right) \nonumber \\ &+ \bar{N}_{\mathrm{s}\bm{k}} - \sqrt{\frac{\bar{T}_\mathrm{s}}{\bar{m}_\mathrm{s}}} \bar{\mu} \bar{\nabla}_\parallel \bar{B} \frac{\partial}{\partial \bar{v}_\parallel} \left( \bar{f}_\mathrm{s} + \frac{\bar{e}_\mathrm{s} \bar{F}_\mathrm{sM}}{\bar{T}_\mathrm{s}} \bar{J}_{0\mathrm{s}} \bar{\phi} \right) \nonumber \\ &+ \frac{e_\mathrm{s} F_\mathrm{sM}}{T_\mathrm{s}} \left[ \sqrt{\frac{\bar{T}_\mathrm{s}}{\bar{m}_\mathrm{s}}} \bar{v}_\parallel \frac{\partial \bar{J}_{0\mathrm{s}} \bar{A}_\parallel}{\partial \bar{t}} - i \bar{\bm{k}} \cdot \bar{\bm{v}}_{\mathrm{s}*} \bar{J}_{0\mathrm{s}} (\bar{\phi} - \sqrt{\frac{\bar{T}_\mathrm{s}}{\bar{m}_\mathrm{s}}} \bar{v}_\parallel \bar{A}_\parallel) \right] = \bar{C}_{\mathrm{s}\bm{k}},\end{split}\]
(2.3) \[\left[ \bar{\lambda}_\mathrm{D}^2 \bar{k}_\perp^2 + \sum_\mathrm{s} \frac{\bar{e}_\mathrm{s}^2 \bar{n}_\mathrm{s}}{\bar{T}_\mathrm{s}} \left( 1 - \bar{\Gamma}_{0\mathrm{s}\bm{k}} \right) \right] \bar{\phi}_{\bm{k}} = \sum_\mathrm{s} \bar{e}_\mathrm{s} \bar{n}_\mathrm{s} \int d\bar{v}^3 \bar{J}_{0\mathrm{s}\bm{k}} \bar{f}_{\mathrm{s}\bm{k}},\]
(2.4) \[\bar{k}_\perp^2 \bar{A}_{\parallel\bm{k}} = \bar{\beta} \sum_\mathrm{s} \bar{e}_\mathrm{s} \bar{n}_\mathrm{s} \int d\bar{v}^3 \bar{J}_{0\mathrm{s}\bm{k}} \sqrt{\frac{\bar{T}_\mathrm{s}}{\bar{m}_\mathrm{s}}} \bar{v}_\parallel \bar{f}_{\mathrm{s}\bm{k}},\]

where we introduced \(\bar{\lambda}_\mathrm{D}^2 = \frac{\lambda_\mathrm{D,ref}^2}{\rho_\mathrm{ref}^2} = \frac{\varepsilon_0 T_\mathrm{ref}/e_\mathrm{ref}^2n_\mathrm{ref}}{\rho_\mathrm{ref}^2}\) and \(\bar{\beta} = \frac{\mu_0 n_\mathrm{ref} T_\mathrm{ref}}{B_\mathrm{ref}^2}\) . The included terms and operators are

(2.5) \[\begin{split}&\bar{\nabla}_\parallel = \frac{\bar{c}_b}{\bar{B} \sqrt{\bar{g}}} \frac{\partial}{\partial z},~~ \bar{k}_\perp^2 = \bar{g}^{xx} \bar{k}_x^2 + 2 \bar{g}^{xy} \bar{k}_x \bar{k}_y + \bar{g}^{yy} \bar{k}_y^2, \nonumber \\ &i \bar{\bm{k}} \cdot (\bar{\bm{v}}_\mathrm{sG} + \bar{\bm{v}}_\mathrm{sC}) = \frac{\bar{T}_\mathrm{s} (\bar{v}_\parallel^2 + \bar{\mu} \bar{B})}{\bar{e}_\mathrm{s} \bar{c}_b} \left( i \bar{K}_x \bar{k}_x + i \bar{K}_y \bar{k}_y \right) + i \frac{\bar{T}_\mathrm{s} \bar{v}_\parallel^2}{\bar{e}_\mathrm{s} \bar{c}_b} \bar{\beta} \frac{d\bar{P}/d\bar{x}}{\bar{B}^2} \bar{k}_y, \nonumber \\ &i \bar{\bm{k}} \cdot \bar{\bm{v}}_\mathrm{s*} = - i \frac{\bar{T}_\mathrm{s}}{\bar{e}_\mathrm{s} \bar{c}_b} \left[ \frac{1}{\bar{L}_{n\mathrm{s}}} + \left( \frac{\bar{v}_\parallel^2}{2} + \bar{\mu} \bar{B} - \frac{3}{2} \right) \frac{1}{\bar{L}_{T\mathrm{s}}} \right] \bar{k}_y, \nonumber \\ &\bar{\mathcal{N}}_{\mathrm{s}\bm{k}} = - \sum_{\bar{\bm{k}}'} \sum_{\bar{\bm{k}}''} \delta_{\bar{\bm{k}}'+\bar{\bm{k}}'',\bar{\bm{k}}}\frac{\bar{\bm{b}} \cdot \bar{\bm{k}}' \times \bar{\bm{k}}''}{\bar{c}_b} \nonumber \\ & \hspace{2cm} \times \bar{J}_{0\mathrm{s}\bm{k}'} \left( \bar{\phi}_{\bm{k}'} - \sqrt{\frac{\bar{T}_\mathrm{s}}{\bar{m}_\mathrm{s}}} \bar{v}_\parallel \bar{A}_{\parallel\bm{k}'} \right) \left( \bar{f}_{\mathrm{s}\bm{k}''} + \frac{\bar{e}_\mathrm{s} \bar{F}_\mathrm{Ms}}{\bar{T}_\mathrm{s}} \bar{J}_{0\mathrm{s}\bm{k}''} \bar{\phi}_{\bm{k}''} \right), \nonumber \\ &\bar{K}_x = - \frac{\partial \ln \bar{B}}{\partial \bar{y}} + \frac{\bar{g}^{xz} \bar{g}^{yx} - \bar{g}^{xx} \bar{g}^{yz}}{\bar{B}^2/\bar{c}_b^2} \frac{\partial \ln \bar{B}}{\partial \bar{z}},~~ \nonumber \\ &\bar{K}_y = \frac{\partial \ln \bar{B}}{\partial \bar{x}} + \frac{\bar{g}^{xz} \bar{g}^{yy} - \bar{g}^{xy} \bar{g}^{yz}}{\bar{B}^2/\bar{c}_b^2} \frac{\partial \ln \bar{B}}{\partial \bar{z}}, \nonumber \\ &\frac{d\bar{P}}{d\bar{x}} = - \sum_\mathrm{s} \bar{n}_\mathrm{s} \bar{T}_\mathrm{s} \left( \frac{1}{\bar{L}_{n\mathrm{s}}} + \frac{1}{\bar{L}_{T\mathrm{s}}} \right),~~ \bar{F}_\mathrm{sM} = \frac{1}{(2\pi)^\frac{3}{2}} e^{-\frac{\bar{v}_\parallel^2}{2}-\bar{\mu}\bar{B}}, \nonumber \\ &\bar{J}_{0\mathrm{s}\bm{k}} = J_0 \left( \bar{k}_\perp \bar{\rho}_\mathrm{s} \right),~~ \bar{\Gamma}_{0\mathrm{s}\bm{k}} = I_0 \left( \bar{k}_\perp^2 \bar{\rho}_\mathrm{ts}^2 \right) e^{- \bar{k}_\perp^2 \bar{\rho}_\mathrm{ts}^2},~~ \nonumber \\ &\bar{\rho}_\mathrm{s} = \sqrt{\frac{2\bar{m}_\mathrm{s}\bar{T}_\mathrm{s}\bar{\mu}}{\bar{e}_\mathrm{s}^2\bar{B}}},~~ \bar{\rho}_\mathrm{ts} = \frac{\sqrt{\bar{m}_\mathrm{s}\bar{T}_\mathrm{s}}}{\bar{e}_\mathrm{s}\bar{B}}\end{split}\]

and the normalized Lenard-Bernstein, Lorentz, and Sugama collision operators are

(2.6) \[\bar{C}_{\mathrm{a}\bm{k}}^\mathrm{LB} = \bar{\nu}_\mathrm{a} \left[ \frac{\partial^2 \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\parallel^2} + \frac{\partial^2 \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\perp^2} + \bar{v}_\parallel \frac{\partial \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\parallel} + \left(\frac{1}{\bar{v}_\perp} + \bar{v}_\perp \right) \frac{\partial \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\perp} + 3 \bar{g}_{\mathrm{a}\bm{k}} - \bar{k}_\perp^2\bar{\rho}_\mathrm{ts}^2 \bar{g}_{\mathrm{a}\bm{k}} \right],\]
(2.7) \[\begin{split}\bar{C}_{\mathrm{a}\bm{k}}^\mathrm{Lorentz} = \bar{\nu}_\mathrm{D}^\mathrm{ab} &\Bigg[ \frac{\bar{v}_\perp^2}{2} \frac{\partial^2 \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\parallel^2} + \frac{\bar{v}_\parallel^2}{2} \frac{\partial^2 \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\perp^2} \nonumber \\ &- \bar{v}_\parallel \bar{v}_\perp \frac{\partial^2 \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\parallel \partial \bar{v}_\perp} - \bar{v}_\parallel \frac{\partial \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\parallel} + \frac{\bar{v}_\perp}{2} \left(\frac{\bar{v}_\parallel^2}{\bar{v}_\perp^2} - 1 \right) \frac{\partial \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\perp} \nonumber \\ &- \frac{\bar{k}_\perp^2\bar{\rho}_\mathrm{ta}^2}{4} (2\bar{v}_\parallel^2+\bar{v}_\perp^2) \bar{g}_{\mathrm{a}\bm{k}} \Bigg],\end{split}\]
(2.8) \[\begin{split}\bar{C}_{\mathrm{a}\bm{k}}^\mathrm{Sugama} &= \sum_\mathrm{b} \left[ C^\mathrm{V}_\mathrm{ab}(\bar{g}_{\mathrm{a}\bm{k}}) + C^\mathrm{D}_\mathrm{ab}(\bar{g}_{\mathrm{a}\bm{k}}) + C^\mathrm{F}_\mathrm{ab}(\bar{g}_{\mathrm{b}\bm{k}}) \right], \\ C^\mathrm{V}_\mathrm{ab}(\bar{g}_{\mathrm{a}\bm{k}}) &= \frac{\bar{\nu}_\parallel^\mathrm{ab}\bar{v}_\parallel^2+\bar{\nu}_\mathrm{D}^\mathrm{ab}\bar{v}_\perp^2}{2}\frac{\partial^2 \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\parallel^2} \nonumber \\ &+ \frac{\bar{\nu}_\mathrm{D}^\mathrm{ab}\bar{v}_\parallel^2+\bar{\nu}_\parallel^\mathrm{ab}\bar{v}_\perp^2}{2}\frac{\partial^2 \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\perp^2} + (\bar{\nu}_\parallel^\mathrm{ab}-\bar{\nu}_\mathrm{D}^\mathrm{ab})\bar{v}_\parallel \bar{v}_\perp \frac{\partial^2 \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\parallel \partial \bar{v}_\perp} \nonumber \\ &+ \bar{\nu}_\mathrm{g}^\mathrm{ab} \bar{v}_\parallel \frac{\partial \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\parallel} + \left[ \bar{\nu}_\mathrm{g}^\mathrm{ab} + \frac{\bar{\nu}_\mathrm{D}^\mathrm{ab}}{2} \left( 1 + \frac{\bar{v}_\parallel^2}{\bar{v}_\perp^2} \right) \right] \bar{v}_\perp \frac{\partial \bar{g}_{\mathrm{a}\bm{k}}}{\partial \bar{v}_\perp} \nonumber \\ &+\left[ \frac{\bar{\nu}_\mathrm{h}^\mathrm{ab} \bar{v}^2}{4} - \frac{\bar{k}_\perp^2\bar{\rho}_\mathrm{ta}^2}{4} \left\{ \bar{\nu}_\mathrm{D}^\mathrm{ab} (2\bar{v}_\parallel^2 + \bar{v}_\perp^2) + \bar{\nu}_\parallel^\mathrm{ab} \bar{v}_\perp^2 \right\} \right] \bar{g}_{\mathrm{a}\bm{k}}, \\ C^\mathrm{D}_\mathrm{ab}(\bar{g}_{\mathrm{a}\bm{k}}) &= \sum_{j=1}^6 \bar{X}_j^\mathrm{ab} \bar{M}_j^\mathrm{ab}, \\ C^\mathrm{F}_\mathrm{ab}(\bar{g}_{\mathrm{b}\bm{k}}) &= \sum_{j=1}^6 \bar{Y}_j^\mathrm{ab} \bar{M}_j^\mathrm{ba}.\end{split}\]

Normalized input parameters for GKV are summarized in Appendix List of GKV namelist .