Charge Conservation

First the charge density of all species with respect to their shape function is computed. Then this charge density is compared to the charge density computed from the divergence of the electric field \(\nabla \vec E\). The maximum deviation value multiplied by the cell’s volume is printed.

Attention

This plugin assumes a Yee-like divergence E stencil!

.cfg file

PIConGPU command line argument (for .cfg files):

--chargeConservation.period <periodOfSteps>

Memory Complexity

Accelerator

no extra allocations (needs at least one FieldTmp slot).

Host

negligible.

Output and Analysis Tools

A new file named chargeConservation.dat is generated:

#timestep max-charge-deviation unit[As]
0 7.59718e-06 5.23234e-17
100 8.99187e-05 5.23234e-17
200 0.000113926 5.23234e-17
300 0.00014836 5.23234e-17
400 0.000154502 5.23234e-17
500 0.000164952 5.23234e-17

The charge is normalized to sim.unit.charge() (third column) which is the typical charge of one macro-particle.

There is a up 5% difference to a native hdf5 post-processing based implementation of the charge conversation check due to a different order of subtraction. And the zero-th time step (only numerical differences) might differ more then 5% relative due to the close to zero result.