Field ionization¶

The goal of this tutorial is to present a simulation using an advanced physics module, namely the field (tunnel) ionization module. In the presence of tunnel ionization, one needs to set a reference temporal/spatial scale. In Smilei, this is done by defining, in SI units, the reference angular frequency parameter: reference_angular_frequency_SI.

Briefly, this tutorial will help you:

use the reference_angular_frequency_SI
use the .getData() tool of happi to analyse your data and make your own figures.

Physical configuration¶

Download the input file tunnel_ionization_1d.py as well as the analysis scripts analysis_tunnel_ionization_1d.py and solve_rate_eqs.py.

In a 1D cartesian geometry, a thin layer of neutral carbon is irradiated (thus ionized) by a linearly-polarized laser pulse with intensity \(I = 5\times 10^{16}~{\rm W/cm^2}\) and a gaussian time profile.

Check the input file and run the simulation¶

The first step is to check that your input file is correct. To do so, you will run (locally) Smilei in test mode:

./smilei_test tunnel_ionization_1d.py

If your simulation input file is correct, you can run the simulation.

Warning

For this simulation, we have specified in the input file that only 1 patch is created. Therefore, this simulation can be run using a single processor only!

Before going to the analysis of your simulation, check your log file!

Analyse the simulation¶

A python script has been prepared to analyse the simulations results. Open the file analysis_tunnel_ionization_1d.py and have look at what it does. Note that it calls for the solve_rate_eqs.py file that is used to compute the rate equations (obtained theoretically).

Warning

Before running analysis_tunnel_ionization_1d.py, give the correct path to your simulation results by defining the simulation_to_analyse variable!

In an ipython prompt, run the analysis file:

%run analysis_tunnel_ionization_1d.py

What do you obtain? Check also if any .eps file is generated.

Note

Some lines containing LateX commands have been commented out. If your machine has LateX installed, it may provide higher-quality figures.

Changing the reference angular frequency¶

As you have seen in the namelist, you have to specify a reference angular frequency in SI units. This because the ionization rate is not invariant under the usual normalizations (see tutorial on Units). What happens to the results if you multiply this frequency by a factor 0.5 or 2.0?