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Diffstat (limited to 'Docs/source/running_cpp/parameters.rst')
| -rw-r--r-- | Docs/source/running_cpp/parameters.rst | 135 |
1 files changed, 98 insertions, 37 deletions
diff --git a/Docs/source/running_cpp/parameters.rst b/Docs/source/running_cpp/parameters.rst index 13088f69c..32ac12104 100644 --- a/Docs/source/running_cpp/parameters.rst +++ b/Docs/source/running_cpp/parameters.rst @@ -171,6 +171,10 @@ Particle initialization Whether particle's weight is varied with their radius. This only applies to cylindrical geometry. The only valid value is true. + * ``predefined``: use one of WarpX predefined plasma profiles. It requires additional + arguments ``<species_name>.predefined_profile_name`` and + ``<species_name>.predefined_profile_params`` (see below). + * ``<species_name>.momentum_distribution_type`` (`string`) Distribution of the normalized momentum (`u=p/mc`) for this species. The options are: @@ -206,6 +210,37 @@ Particle initialization * If ``true``, each particle is advanced with the average speed of the species ``vzbar`` until it reaches ``zinject_plane``. +* ``species_name.predefined_profile_name`` (`string`) + Only read of ``<species_name>.electrons.profile`` is `predefined`. + + * If ``parabolic_channel``, the plasma profile is a parabolic profile with linear ramps + at the beginning and the end of the profile. The density is given by + + .. math:: + + n = n_0 n(x,y) n(z) + + with + + .. math:: + + n(x,y) = 1 + 4\frac{x^2+y^2}{k_p^2 R_c^4} + + where :math:`k_p` is the plasma wavenumber associated with density :math:`n_0`. + Here, :math:`n(z)` is a linear up-ramp from :math:`0` to :math:`L_{ramp,up}`, + constant to :math:`1` from :math:`L_{ramp,up}` to :math:`L_{ramp,up} + L_{plateau}` + and a linear down-ramp from :math:`L_{ramp,up} + L_{plateau}` to + :math:`L_{ramp,up} + L_{plateau}+L_{ramp,down}`. All parameters are given + in ``predefined_profile_params``. + +* ``<species_name>.predefined_profile_params`` (list of `float`) + Parameters for the predefined profiles. + + * If ``species_name.predefined_profile_name`` is ``parabolic_channel``, + ``predefined_profile_params`` contains a space-separated list of the + following parameters, in this order: :math:`L_{ramp,up}` :math:`L_{plateau}` + :math:`L_{ramp,down}` :math:`R_c` :math:`n_0` + * ``<species_name>.do_backward_injection`` (`bool`) Inject a backward-propagating beam to reduce the effect of charge-separation fields when running in the boosted frame. See examples. @@ -225,28 +260,35 @@ Particle initialization Laser initialization -------------------- -* ``warpx.use_laser`` (`0 or 1`) optional (default `0`) - Whether to activate the injection of a laser pulse in the simulation +* ``lasers.nlasers`` (`int`) optional (default `0`) + Number of lasers pulses. + +* ``lasers.names`` (list of `string`. Must contain ``lasers.nlasers`` elements) + Name of each laser. This is then used in the rest of the input deck ; + in this documentation we use `<laser_name>` as a placeholder. The parameters below + must be provided for each laser pulse. -* ``laser.position`` (`3 floats in 3D and 2D` ; in meters) +* ```<laser_name>`.position`` (`3 floats in 3D and 2D` ; in meters) The coordinates of one of the point of the antenna that will emit the laser. - The plane of the antenna is entirely defined by ``laser.position`` and ``laser.direction``. + The plane of the antenna is entirely defined by ``<laser_name>.position`` + and ``<laser_name>.direction``. - ``laser.position`` also corresponds to the origin of the coordinates system + ```<laser_name>`.position`` also corresponds to the origin of the coordinates system for the laser tranverse profile. For instance, for a Gaussian laser profile, - the peak of intensity will be at the position given by ``laser.position``. + the peak of intensity will be at the position given by ``<laser_name>.position``. This variable can thus be used to shift the position of the laser pulse transversally. .. note:: - In 2D, ``laser.position`` is still given by 3 numbers, but the second number is ignored. + In 2D, ```<laser_name>`.position`` is still given by 3 numbers, + but the second number is ignored. When running a **boosted-frame simulation**, provide the value of - ``laser.position`` in the laboratory frame, and use ``warpx.gamma_boost`` + ``<laser_name>.position`` in the laboratory frame, and use ``warpx.gamma_boost`` to automatically perform the conversion to the boosted frame. Note that, in this case, the laser antenna will be moving, in the boosted frame. -* ``laser.polarization`` (`3 floats in 3D and 2D`) +* ``<laser_name>.polarization`` (`3 floats in 3D and 2D`) The coordinates of a vector that points in the direction of polarization of the laser. The norm of this vector is unimportant, only its direction matters. @@ -254,7 +296,7 @@ Laser initialization Even in 2D, all the 3 components of this vectors are important (i.e. the polarization can be orthogonal to the plane of the simulation). -* ``laser.direction`` (`3 floats in 3D`) +* ``<laser_name>.direction`` (`3 floats in 3D`) The coordinates of a vector that points in the propagation direction of the laser. The norm of this vector is unimportant, only its direction matters. @@ -262,10 +304,10 @@ Laser initialization .. warning:: - When running **boosted-frame simulations**, ``laser.direction`` should + When running **boosted-frame simulations**, ``<laser_name>.direction`` should be parallel to ``warpx.boost_direction``, for now. -* ``laser.e_max`` (`float` ; in V/m) +* ``<laser_name>.e_max`` (`float` ; in V/m) Peak amplitude of the laser field. For a laser with a wavelength :math:`\lambda = 0.8\,\mu m`, the peak amplitude @@ -275,45 +317,45 @@ Laser initialization E_{max} = a_0 \frac{2 \pi m_e c}{e\lambda} = a_0 \times (4.0 \cdot 10^{12} \;V.m^{-1}) - When running a **boosted-frame simulation**, provide the value of ``laser.e_max`` + When running a **boosted-frame simulation**, provide the value of ``<laser_name>.e_max`` in the laboratory frame, and use ``warpx.gamma_boost`` to automatically perform the conversion to the boosted frame. -* ``laser.wavelength`` (`float`; in meters) +* ``<laser_name>.wavelength`` (`float`; in meters) The wavelength of the laser in vacuum. When running a **boosted-frame simulation**, provide the value of - ``laser.wavelength`` in the laboratory frame, and use ``warpx.gamma_boost`` + ``<laser_name>.wavelength`` in the laboratory frame, and use ``warpx.gamma_boost`` to automatically perform the conversion to the boosted frame. -* ``laser.profile`` (`string`) +* ``<laser_name>.profile`` (`string`) The spatio-temporal shape of the laser. The options that are currently implemented are: - ``"Gaussian"``: The transverse and longitudinal profiles are Gaussian. - ``"Harris"``: The transverse profile is Gaussian, but the longitudinal profile - is given by the Harris function (see ``laser.profile_duration`` for more details) + is given by the Harris function (see ``<laser_name>.profile_duration`` for more details) - ``"parse_field_function"``: the laser electric field is given by a function in the - input file. It requires additional argument ``laser.field_function(X,Y,t)``, which + input file. It requires additional argument ``<laser_name>.field_function(X,Y,t)``, which is a mathematical expression , e.g. - ``laser.field_function(X,Y,t) = "a0*X**2 * (X>0) * cos(omega0*t)"`` where + ``<laser_name>.field_function(X,Y,t) = "a0*X**2 * (X>0) * cos(omega0*t)"`` where ``a0`` and ``omega0`` are a user-defined constant, see above. The profile passed here is the full profile, not only the laser envelope. ``t`` is time and ``X`` - and ``Y`` are coordinates orthogonal to ``laser.direction`` (not necessarily the + and ``Y`` are coordinates orthogonal to ``<laser_name>.direction`` (not necessarily the x and y coordinates of the simulation). All parameters above are required, but - none of the parameters below are used when ``laser.parse_field_function=1``. Even - though ``laser.wavelength`` and ``laser.e_max`` should be included in the laser + none of the parameters below are used when ``<laser_name>.parse_field_function=1``. Even + though ``<laser_name>.wavelength`` and ``<laser_name>.e_max`` should be included in the laser function, they still have to be specified as they are used for numerical purposes. -* ``laser.profile_t_peak`` (`float`; in seconds) +* ``<laser_name>.profile_t_peak`` (`float`; in seconds) The time at which the laser reaches its peak intensity, at the position - given by ``laser.position`` (only used for the ``"gaussian"`` profile) + given by ``<laser_name>.position`` (only used for the ``"gaussian"`` profile) When running a **boosted-frame simulation**, provide the value of - ``laser.profile_t_peak`` in the laboratory frame, and use ``warpx.gamma_boost`` + ``<laser_name>.profile_t_peak`` in the laboratory frame, and use ``warpx.gamma_boost`` to automatically perform the conversion to the boosted frame. -* ``laser.profile_duration`` (`float` ; in seconds) +* ``<laser_name>.profile_duration`` (`float` ; in seconds) The duration of the laser, defined as :math:`\tau` below: @@ -330,42 +372,61 @@ Laser initialization E(\boldsymbol{x},t) \propto \frac{1}{32}\left[10 - 15 \cos\left(\frac{2\pi t}{\tau}\right) + 6 \cos\left(\frac{4\pi t}{\tau}\right) - \cos\left(\frac{6\pi t}{\tau}\right) \right]\Theta(\tau - t) When running a **boosted-frame simulation**, provide the value of - ``laser.profile_duration`` in the laboratory frame, and use ``warpx.gamma_boost`` + ``<laser_name>.profile_duration`` in the laboratory frame, and use ``warpx.gamma_boost`` to automatically perform the conversion to the boosted frame. -* ``laser.profile_waist`` (`float` ; in meters) +* ``<laser_name>.profile_waist`` (`float` ; in meters) The waist of the transverse Gaussian laser profile, defined as :math:`w_0` : .. math:: E(\boldsymbol{x},t) \propto \exp\left( -\frac{\boldsymbol{x}_\perp^2}{w_0^2} \right) -* ``laser.profile_focal_distance`` (`float`; in meters) +* ``<laser_name>.profile_focal_distance`` (`float`; in meters) The distance from ``laser_position`` to the focal plane. - (where the distance is defined along the direction given by ``laser.direction``.) + (where the distance is defined along the direction given by ``<laser_name>.direction``.) Use a negative number for a defocussing laser instead of a focussing laser. When running a **boosted-frame simulation**, provide the value of - ``laser.profile_focal_distance`` in the laboratory frame, and use ``warpx.gamma_boost`` + ``<laser_name>.profile_focal_distance`` in the laboratory frame, and use ``warpx.gamma_boost`` to automatically perform the conversion to the boosted frame. -* ``laser.stc_direction`` (`3 floats`) optional (default `1. 0. 0.`) +* ``<laser_name>.stc_direction`` (`3 floats`) optional (default `1. 0. 0.`) Direction of laser spatio-temporal couplings. See definition in Akturk et al., Opt Express, vol 12, no 19 (2014). -* ``laser.zeta`` (`float`; in meters.seconds) optional (default `0.`) - Spatial chirp at focus in direction ``laser.stc_direction``. See definition in +* ``<laser_name>.zeta`` (`float`; in meters.seconds) optional (default `0.`) + Spatial chirp at focus in direction ``<laser_name>.stc_direction``. See definition in Akturk et al., Opt Express, vol 12, no 19 (2014). -* ``laser.beta`` (`float`; in seconds) optional (default `0.`) - Angular dispersion (or angular chirp) at focus in direction ``laser.stc_direction``. +* ``<laser_name>.beta`` (`float`; in seconds) optional (default `0.`) + Angular dispersion (or angular chirp) at focus in direction ``<laser_name>.stc_direction``. See definition in Akturk et al., Opt Express, vol 12, no 19 (2014). -* ``laser.phi2`` (`float`; in seconds**2) optional (default `0.`) +* ``<laser_name>.phi2`` (`float`; in seconds**2) optional (default `0.`) Temporal chirp at focus. See definition in Akturk et al., Opt Express, vol 12, no 19 (2014). +* ``warpx.num_mirrors`` (`int`) optional (default `0`) + Users can input perfect mirror condition inside the simulation domain. + The number of mirrors is given by ``warpx.num_mirrors``. The mirrors are + orthogonal to the `z` direction. The following parameters are required + when ``warpx.num_mirrors`` is >0. + +* ``warpx.mirror_z`` (list of `float`) required if ``warpx.num_mirrors>0`` + ``z`` location of the front of the mirrors. + +* ``warpx.mirror_z_width`` (list of `float`) required if ``warpx.num_mirrors>0`` + ``z`` width of the mirrors. + +* ``warpx.mirror_z_npoints`` (list of `int`) required if ``warpx.num_mirrors>0`` + In the boosted frame, depending on `gamma_boost`, ``warpx.mirror_z_width`` + can be smaller than the cell size, so that the mirror would not work. This + parameter is the minimum number of points for the mirror. If + ``mirror_z_width < dz/cell_size``, the upper bound of the mirror is increased + so that it contains at least ``mirror_z_npoints``. + Numerics and algorithms ----------------------- |