# Analysis of DRP signals, analysis of particle transport¶

The following script shows the basic data aquision from Double Rake Probe

To get more detailed information about Double Rake Probe visit its wikipage.

DRP consists of two rakes of Langmuir probes that can be operated in two basic modes.
The first one is floating potential mode ($V_\mathrm{float}$), where each pin is insulated
and we can measure an approximation of plasma potential.

The other mode is ion saturation current ($I_\mathrm{sat}$), where -100 V voltage is
applied to each pin. This voltage repels electrons so one can measure the plasma density.

To measure transport using DRP one has to measure 4 floating potential ($V_\mathrm{fl}$)
signals and 2 ion saturation current ($I_\mathrm{sat}$) signals, however, quality $I_\mathrm{sat}$
measurements may turn out to be challenging to perform, so in the following
script, only $V_\mathrm{float}$ measurements are considered.

### Needed Python modules¶

One might need to modify ulr_base variable in download_data function and the channel names in channel_list.

The correct url_base depends on the DAS used and the channel_list
represents the names of particular signals.
It is recommended to save the data to your computer if runnig the scipts locally,
as it saves time and makes your analysis independent on internet connection.

Eventually the data is converted into xarray.DataArray structure for convenience.

we keep using the signal order and time window from the cell above → so we continue to work with the sel_plasma variable