Copy of a documentation mail to a user:


**What is the unit system of our output?**

PIConGPU outputs it's data in hdf5 (and adios) per default in SI.

To get the SI unit, you need to multiply the data set you are accessing
with "sim_unit" for each entry it has. "sim_unit" is an attributed
stored alongside it.

For scalar fields such as densities, etc. it is currently not well
documented, but most of them were until recently charge-densities or
charge-energy-densities.

This is just changed just a few weeks ago (and the latest dev version
already received some updates with #1259). But you should as a user
better work on `master` if it fits your requirements since `dev` is
experimental and we can barely support `dev` as a moving target in
comparison to the stable releases (0.1.1). Maybe you are already working
on that (experimental) version?

Additionally and for the next release (0.2.0), there will be a major
improvement. I am currently implementing a fully-documented output
format called "openPMD" but this will be first available in
Januar/February for a stable release

  https://github.com/openPMD/openPMD-standard


**How to output the current density**

yes of course you can!

just edit your `fileOutput.param` in your simulation case
  (the default is stored here:
    src/picongpu/include/simulation_defines/param/fileOutput.param)

and adjust the line http://git.io/vEGWb
  typedef MakeSeq<FieldE, FieldB>::type NativeFileOutputFields;
to read
  typedef MakeSeq<FieldE, FieldB, FieldJ>::type NativeFileOutputFields;


Cheers,
Axel