.. _physics_glossary: .. Automatically generated by VariableConsistencyChecker based on variables.yaml. Do not edit this file by hand! Physics Glossary ================== .. glossary:: :sorted: alpha_t Turbulence characterization parameter used by the separatrix operational space. areal_elongation Elongation of the confined region computed using the poloidal area inside the last-closed-flux-surface :math:`\kappa_A = S_{pol} / (\pi a^2)`. atomic_data Dictionary mapping :class:`~cfspopcon.named_options.AtomicSpecies` to datasets giving coronal and non-coronal :math:`L_z` radiated power factors and :math:`\langle Z \rangle` mean charge state curves from `radas `_. average_electron_density Volume-averaged electron density in the confined region :math:`\bar n_e`. average_electron_temp Volume-averaged electron temperature in the confined region :math:`\bar T_e`. average_ion_density Volume-averaged ion density in the confined region :math:`\bar n_i`. average_ion_mass Average mass of fuel ions, with the average weighted by the relative concentration of each species. average_ion_temp Volume-averaged ion temperature in the confined region :math:`\bar T_i`. average_total_pressure Sum of electron and ion pressures. B_pol_out_mid Poloidal magnetic field at outboard midplane separatrix B_t_out_mid Toroidal magnetic field at outboard midplane separatrix beta_poloidal Ratio of plasma pressure to magnetic pressure provided by the poloidal magnetic field. beta_toroidal Ratio of plasma pressure to magnetic pressure provided by the toroidal magnetic field. beta_total Ratio of plasma pressure to magnetic pressure provided by the total magnetic field. bootstrap_fraction Fraction of the plasma current due to the bootstrap current. breakdown_flux_consumption From a point model estimate given by :cite:`Sugihara`, this expression gives the required flux for ionization. change_in_dilution Change in the fuel-ion dilution, resolved per impurity species. change_in_zeff Change in the effective charge, resolved per impurity species. confinement_power_scaling A :class:`~cfspopcon.named_options.ConfinementPowerScaling` indicating which confinement mode power-threshold scaling to use. confinement_threshold_scalar Scalar value applied to the confinement threshold (:math:`P_{LH}` or :math:`P_{LI}`), used to study the effect of increasing or decreasing the threshold. confinement_time_scalar Usually denoted :math:`H`, scalar applied to the energy confinement time calculated from a scaling such that :math:`\tau_e = H \tau_{e,scaling}`. core_impurity_species A :class:`~cfspopcon.named_options.AtomicSpecies` indicating which species should be used as the core radiator core_radiated_power_fraction Fraction of input power radiated from the confined region before it reaches the separatrix. critical_alpha_MHD Critical value of :math:`\alpha_{MHD}` used in the separatrix operational space. current_relaxation_time Time constant for the radial current diffusion. cylindrical_safety_factor Analytical approximation of safety factor at :math:`\rho=0.95` (confusingly, still has some shaping corrections despite being called the 'cylindrical' safety factor). density_profile_form A :class:`~cfspopcon.named_options.ProfileForm` indicating which sort of assumed profile shape we should use for the density profiles. dilution Fuel-species concentration as a fraction of the electron density :math:`n_{DT}/n_e`. edge_collisionality Collisionality at the separatrix. edge_impurity_concentration Concentration of the edge radiator (impurity density relative to the electron density) in the edge. edge_impurity_concentration_in_core Concentration of the edge-radiator impurity in the core, after applying a compression/enrichment factor. edge_impurity_enrichment Ratio of concentration of the edge radiator in the core to in the edge, :math:`f_e = n_{edge}/n_{core}`. edge_impurity_species A :class:`~cfspopcon.named_options.AtomicSpecies` indicating which species should be injected into the plasma to increase the power radiated from the confined region. effective_collisionality Estimate of collisionality used for computing the expected density peaking. ejima_coefficient Empirical linear scaling factor of the product of major radius and plasma current at flattop correlated with resistive flux at start of flattop :math:`C_E`. electron_density_peaking Ratio of the peak ion density to the volume-averaged electron density. electron_density_peaking_offset Scalar offset of the electron density peaking relative to the density peaking scaling. electron_density_profile A 1D profile of the electron density as a function of :math:`\rho_{pol}`. electron_temp_profile A 1D profile of the electron temperature as a function of :math:`\rho_{pol}`. elongation_psi95 Usually denoted :math:`\kappa_{95}`, the elongation at the :math:`\psi_N=0.95` surface. elongation_ratio_areal_to_psi95 Ratio of areal elongation to elongation at the :math:`\psi_N=0.95` surface, :math:`\kappa_{A}/\kappa_{95}`. elongation_ratio_sep_to_areal Ratio of separatrix elongation to areal elongation :math:`\kappa_{sep}/\kappa_A`. energy_confinement_scaling Which :math:`\tau_e` energy confinement scaling should be used. Should match a confinement scaling in `cfspopcon.formulas.energy_confinement::energy_confinement_scalings.yaml`. energy_confinement_scaling_for_L_mode Which :math:`\tau_e` energy confinement scaling should be used if :math:`P_{SOL} < P_{LH}`. Should match an L-mode confinement scaling in `cfspopcon.formulas.energy_confinement::energy_confinement_scalings.yaml`. energy_confinement_time A characteristic time which gives the rate at which the plasma loses energy. In steady-state, :math:`\tau_e=W_p / P_in`. external_flux The flux from the time integration of the voltage due to the external inductance of the plasma. The general formula is the time integration of :math:`- L_e\frac{dI_p}{dt} - Ip\frac{dL_e}{dt}` Note, time-independent POPCON makes the simplification that :math:`L_e` is constant over the ramp-up. external_inductance The self-inductance associated with the LCFS of the plasma. f_shaping Shaping factor used to compute :math:`q_*`. fieldline_pitch_at_omp The magnetic field pitch :math:`B_{tot} / B_{pol}` at the 'upstream' end of a flux tube in the scrape-off-layer, used to convert from poloidal to parallel heat flux density. flux_needed_from_CS_over_rampup The amount of flux needed from the CS over ramp up. fraction_of_external_power_coupled Fraction of supplied external heating absorbed by the plasma: :math:`f_{coupled}=P_{external} / P_{launched}`. fraction_of_P_SOL_to_divertor fraction of the total power going towards the most-loaded divertor target. fuel_ion_density_profile A 1D profile of the fuel ion density as a function of :math:`\rho_{pol}`. fusion_reaction A `str` indicating which fusion reaction should be used, should match a class name in `cfspopcon.formulas.fusion_reaction.fusion_data` fusion_triple_product The product of the energy confinement time, the core ion temperature and core ion density, used as a metric for fusion performance. greenwald_density_limit The highest volume-averaged density which can be achieved before a density-limit disruption is triggered. greenwald_fraction Ratio of the average electron density to the Greenwald density limit :math:`f_{G}=\bar n_e / n_G`. heavier_fuel_species_fraction Fraction of fuel ions which are the heavier species. i.e. for DT fusion, this is :math:`f_T = n_T/(n_T+n_D)`. impurity_charge_state The mean charge state of a non-fuel species. impurity_concentration Concentration of each impurity species, relative to the electron density. impurity_residence_time The average time an impurity ion stays in the scrape-off-layer before it recycles on the wall. impurity_species A :class:`~cfspopcon.named_options.AtomicSpecies` indicating which impurity to use for a calculation. inductive_plasma_current Plasma current driven by the central solenoid (i.e. excluding the contribution of the bootstrap current). internal_flux The flux from the time integration of the voltage due to the internal inductance of the plasma. The general formula is the time integration of :math:`- L_i\frac{dI_p}{dt} - \frac{Ip}{2}\frac{dL_i}{dt}` Note, time-independent POPCON makes the simplification that :math:`L_i` is constant over the ramp-up. internal_inductance The self-inductance of the plasma from the center to the plasma edge. internal_inductivity Also known as normalized internal inductance, for a general geometry, is :math:`\frac{\langle B^2_{\theta} \rangle _V}{\langle B_{\theta}(r=LCFS) \rangle}` but is approximated in POPCON for a cylindrical plasma. intrinsic_impurity_concentration Concentration of each intrinsic impurity species, relative to the electron density. inverse_aspect_ratio Ratio of minor to major radius :math:`\epsilon= a / R_0`. invmu_0_dLedR :math:`\frac{1}{\mu_0}\frac{\partial L_e}{\partial R}` (eq.21 in :cite:`Barr_2018`) which is a part of the hoop force and therefore appears in the :term:`vertical_magnetic_field_equation` which counteracts the outward toroidal forces. ion_density_peaking Ratio of the peak ion density to the volume-averaged ion density. ion_density_peaking_offset Scalar offset of the ion density peaking relative to the density peaking scaling. ion_heat_diffusivity A heat diffusion constant which gives a heat flux corresponding to an ion temperature gradient. ion_temp_profile A 1D profile of the ion temperature as a function of :math:`\rho_{pol}`. ion_to_electron_temp_ratio Ratio of electron and ion temperatures, :math:`T_i/T_e`. ionization_volume Volume available above the target for ionization ionization_volume_density_factor factor that relates the target density to an averaged density across the ionization volume kappa_e0 Electron heat conductivity constant, such that :math:`q_{e,\parallel,cond}=\kappa_{e0}T_{e}^{5/2}\nabla_\parallel T_e`. kappa_ez finite z correction factor to the electron heat conductivity. per :cite:`Goldston_2017` lambda_q The near-scrape-off-layer heat-flux-density decay length. lambda_q_factor A scaling factor :math:`C` which can be used to increase or decrease :math:`\lambda_q=C \lambda_{q,scaling}`. lambda_q_scaling A :class:`~cfspopcon.named_options.LambdaQScaling` indicating which scaling to use for calculating :term:`lambda_q`. lengyel_overestimation_factor A constant calibration factor applied to the impurity concentration calculated by the Lengyel model such that its value approximately matches the value calculated by higher fidelity modelling such as SOLPS. loop_voltage inductive loop voltage magnetic_field_on_axis Magnetic field at the geometric magnetic axis :math:`B_0 = BR / R0`. major_radius The major radius of the geometric magnetic axis. max_flattop_duration Given the loop voltage at flattop, and how much flux from the CS has been consumed over the ramp-up, this defines how long your flattop can be. maximum_P_LH_factor_for_P_SOL If P_SOL is larger than this factor times the P_LH threshold, core impurities will be seeded to reduce P_SOL to th mean_ion_charge_state Mean charge state of the ions (:math:`n_e / \sum_j n_j`) min_P_radiation The minimum amount of power which must be radiated from the confined region. If power radiated by the intrinsic impurities is less than this, a core radiator will be injected until this level is reached. minimum_core_radiated_fraction Minimum fraction of :math:`P_{in}` which should be radiated from the confined region, below which we will inject an additional core radiator to increase the radiated power up to this value. minor_radius Horizontal minor radius of the plasma :math:`(R_{max,LCFS}-R_{min,LCFS})/2` n_points_for_confined_region_profiles The number of points to use for the confined region profiles. neoclassical_loop_resistivity Plasma loop neoclassical resistivity. nesep_over_nebar Ratio of the separatrix electron density to the volume-averaged electron density :math:`n_{e,sep} / \bar n_e`. neutral_flux_density_factor Conversion factor from neutral pressure at duct to neutral recycling flux at the target. From :cite:`Kallenbach_2018` neutron_power_flux_to_walls Neutron power per unit area to the wall. neutron_rate Number of neutrons produced per second. normalized_beta Ratio of plasma pressure to magnetic pressure provided by the total magnetic field, normalized to :math:`\beta_{max} = I_MA / a B_0` (Troyon limit). normalized_inverse_temp_scale_length Inverse normalized electron temperature gradient scale length :math:`a / ( T_e / \nabla T_e )`, which defines the shape of the :class:`~cfspopcon.named_options.ProfileForm.prf` profiles. nu_star The normalized collisionality. P_alpha Fusion power released as alpha particles integrated over the plasma volume. P_auxiliary_absorbed auxiliary heating absorbed by the plasma integrated over the plasma volume. P_auxiliary_launched External heating supplied to the plasma (entering the volume, but not necessarily absorbed by the plasma) integrated over the plasma volume. P_external External heating absorbed by the plasma (ohmic plus auxiliary) integrated over the plasma volume. P_fusion Total power generated by fusion integrated over the plasma volume. For DT fusion, this is the sum of the power going to the alpha particles and to the neutrons. P_in Total input power to the plasma. Sum of ohmic, auxiliary and alpha power. P_LH_thresh Power required to cross the L-H transition. P_LI_thresh Power required to cross the L-I transition. P_neutron Fusion power released as neutrons integrated over the plasma volume. P_ohmic Power deposited in the plasma due to resistive ohmic heating. P_rad_bremsstrahlung Power radiated due to Bremmsstrahlung from all species. P_rad_hydrogen_bremsstrahlung Power radiated due to Bremmsstrahlung from hydrogen. P_rad_impurity Power radiated by impurities in the plasma. P_rad_synchrotron Power radiated due to synchrotron radiation. P_radiation Power radiated from the confined region due to Bremmsstrahlung, synchrotron and impurity excitation-relaxation processes. P_radiation_from_core_seeded_impurity The power radiated by the core radiator. parallel_connection_length Parallel length (along a field-line) of a scrape-off-layer flux tube, from an 'upstream' position (usually the outboard midplane) to the divertor target. PB_over_R :math:`P_{SOL}B_0/R`, a metric used to estimate how challenging heat exhaust will be. PBpRnSq :math:`P_{SOL}B_{pol}/(R n_{sep}^2)`, a metric used to estimate how challenging heat exhaust will be. This metric is approximately :math:`q_\parallel/n_{e,sep}^2`, which in the Lengyel model gives the impurity concentration required for detachment. peak_electron_density Peak electron density peak_electron_temp Peak electron temperature peak_fuel_ion_density Peak fuel ion density (i.e. product of fuel dilution, ion peaking factor and average electron density). peak_ion_temp Peak ion temperature peak_pressure Peak total pressure in the core. plasma_current Current carried by the plasma :math:`I_p`. plasma_stored_energy Thermal energy in the plasma. plasma_volume Plasma volume inside the last-closed-flux-surface. poloidal_circumference Plasma poloidal circumference of the LCFS. poloidal_field_flux The surface flux contribution from the vertical magnetic field required for radial force balance (which arises from the poloidal field coils). poloidal_sound_larmor_radius The sound Larmor radius using the poloidal magnetic field. power_crossing_separatrix Power crossing the separatrix and entering the scrape-off-layer. pumping_duct_neutral_pressure Neutral pressure at the baratron position in pumping duct. Q Fusion power thermal gain factor. q_parallel The parallel heat flux density entering a scrape-off-layer flux tube. q_perp The poloidal heat flux density entering a scrape-off-layer flux tube. q_star Analytical approximation of safety factor at :math:`\rho=0.95`. radas_dir A path to the `radas `_ working directory. radas_version Version of radas used to construct the atomic data files. radiated_power_method A :class:`~cfspopcon.named_options.RadiationMethod` indicating how we should calculate the power radiated from the confined region. radiated_power_scalar An enhancement factor :math:`C` to modify the radiated power :math:`P_{rad} = C P_{rad,calculated}`. ratio_of_divertor_to_duct_pressure ratio between divertor neutral pressure and pressure at pumping duct ratio_of_molecular_to_ion_mass Ratio between neutral molecule mass and ion mass ratio_of_P_SOL_to_P_LH The ratio of the power crossing the separatrix to the LH transition threshold power. ratio_of_P_SOL_to_P_LI The ratio of the power crossing the separatrix to the LI transition threshold power. reattachment_time Time duration for detachment front to reach the target in response to a transient. Per :cite:`Henderson_2023` reference_electron_density A constant upstream electron density used when evaluating the :math:`L_Z` impurity radiation curve (due to the reasonably weak dependence of :math:`L_Z` on :math:`n_e`, this approximation shouldn't be too harmful). reference_ne_tau A constant :math:`n_e\tau` (upstream electron density times impurity residence time) used when evaluating the :math:`L_Z` impurity radiation curve. resistive_flux Usually this is the magnetic flux induced by the resistance of the plasma. However, given that POPCON calculates this with the empirical :math:`C_E`, it may also hold information about flux induced coupling with the wall. :math:`\psi_{res} = C_E\mu_0R_0I_p`. resistivity_trapped_enhancement_method A flag to indicate which method should be used when calculating the enhancement of resistivity due to trapped particles. rho The square-root of the normalized poloidal flux :math:`\rho_{pol}=\sqrt{\psi_N}`, used as a flux surface label. rho_star The ratio of the sound Larmor radius to the major radius for the average ion temperature. safety_factor_on_axis On-axis safety factor separatrix_electron_density The electron density at the 'upstream' end of a scrape-off-layer flux-tube (usually at the outboard midplane). separatrix_electron_temp The electron temperature at the 'upstream' end of a scrape-off-layer flux-tube (usually at the outboard midplane). separatrix_elongation Elongation of the last-closed-flux-surface :math:`(Z_{max,LCFS} - Z_{min,LCFS}) / (R_{max,LCFS} - R_{min,LCFS})`. separatrix_power_transient Transient increase to power crossing the separatrix. Per :cite:`Henderson_2023` separatrix_triangularity Separatrix triangularity (average of upper and lower triangularity). SepOS_density_limit Less than 1 if an L-mode is below the density limit, according to the separatrix operational space. SepOS_LH_transition Less than 1 if in L-mode and greater than 1 if in H-mode, according to the separatrix operational space. SepOS_MHD_limit Less than 1 if below the ideal MHD limit, according to the separatrix operational space. sheath_heat_transmission_factor Sheath heat transmission coefficient per equation 2.89 in :cite:`Stangeby_2000` SOC_LOC_ratio Ratio of the energy confinement time from the chosen saturated ohmic confinement (SOC) scaling and the chosen linear ohmic confinement (LOC) scaling. SOL_conduction_fraction Fraction of power carried by heat conduction in the scrape-off-layer. SOL_momentum_loss_function Fraction of momentum entering a scrape-off-layer flux tube which is lost before reaching the divertor target. SOL_power_loss_fraction Fraction of power entering a scrape-off-layer flux tube which is lost (radiated or cross-field transported) before reaching the divertor target. spitzer_resistivity Plasma loop collisional resistivity. summed_impurity_density Density of non-fuel ions. surface_area Area of the last-closed-flux-surface, i.e. the surface defined by toroidally revolving the poloidal last-closed-flux-surface. surface_inductance_coefficients The set of coefficients from Hirshman :cite:`hirshman` or Barr's :cite:`Barr_2018` paper on external flux which are used to fit analytic expressions, dependent on plasma geometry, to the external inductance and vertical field mutual inductance of the plasma. sustainment_power_in_electron_channel The power in the electron channel required to maintain the electron temperature at the separatrix. sustainment_power_in_ion_channel The power in the ion channel required to maintain the ion temperature gradient at the separatrix. target_angle_of_incidence Angle of incidence between magnetic field vector and surface normal vector at divertor target. target_electron_density The electron density at the divertor target. target_electron_flux The rate of electrons per unit area reaching the divertor target. target_electron_temp The electron temperature at the divertor target. target_gaussian_spreading Gaussian spreading coefficient, S, representing diffusive transport between x-point and divertor target target_neutral_pressure Neutral pressure at the divertor target. target_q_parallel The parallel heat flux density at the divertor target. temp_profile_form A :class:`~cfspopcon.named_options.ProfileForm` indicating which sort of assumed profile shape we should use for the temperature profiles. temp_scale_length_ratio The ratio of the electron and ion temperature scale lengths at the separatrix :math:`T_i / T_e * \lambda_{T_e} / \lambda_{T_i} = L_{T_e} / L_{T_i}`. temperature_peaking Ratio of the peak (electron or ion) temperature to the volume-averaged temperature. toroidal_flux_expansion Ratio of the divertor target major radius to the 'upstream' (usually outboard midplane) major radius for the two point model :math:`R_{target} / R_{upstream}`. total_flux_available_from_CS The amount of flux available from the central solenoid over the entire pulse. trapped_particle_fraction Global average of the fraction of trapped electrons used in the calculation of global plasma resistivity. triangularity_psi95 Usually denoted :math:`\delta_{95}`, average of upper and lower triangularity at the :math:`\psi_N=0.95` surface. triangularity_ratio_sep_to_psi95 Ratio of separatrix triangularity to triangularity at the :math:`psi_N=0.95` surface :math:`\delta_{sep}/\delta_{95}.` troyon_max_beta The Troyon beta limit. two_point_model_error_nonconverged_error Indicates whether the two-point-model should raise an error or return NaN if its iterative solver does not converge. vertical_field_mutual_inductance This unitless mutual-inductance quantity provides the coupling between the plasma surface and the vertical magnetic field. vertical_magnetic_field Vertical magnetic field derived from the necessary force to balance the hoop force :math:`B_V` vertical_magnetic_field_equation Which vertical magnetic field equation to select from :cite:`mit&taka`, :cite:`Barr_2018`, :cite:`Jean`, :cite:`MFEF` vertical_minor_radius Vertical minor radius of the plasma :math:`(Z_{max,LCFS}-Z_{min,LCFS})/2` wall_temperature Temperature of neutral gas at the wall z_effective The "effective charge" of the ions, defined as :math:`\sum_j Z_j^2 n_j / n_e`.