


```python
import DREAM
import numpy as np

# Construct the DREAM object
ds = DREAM.DREAMSettings()

# Set the electric field
ds.eqsys.E_field.setPrescribedData(0.6)

# Set the electron density
ds.eqsys.n_i.addIon('D', Z=1, n=5e19, iontype=DREAM.Ions.IONS_PRESCRIBED_FULLY_IONIZED)

# Set the temperature
ds.eqsys.T_cold.setPrescribedData(1e3)

# Disable the hot-tail grid
ds.hottailgrid.setEnabled(False)

# Set the collision frequency mode to ultra-relativistic
ds.collisions.collfreq_mode = DREAM.Collisions.COLLFREQ_MODE_ULTRA_RELATIVISTIC

# Include the Dreicer and avalanche effects
ds.eqsys.n_re.setAvalanche(DREAM.Avalanche.AVALANCHE_MODE_FLUID)
ds.eqsys.n_re.setDreicer(DREAM.DREAM.DREAM_NAME_NEURAL_NETWORK)

# Set the initial profile
ds.eqsys.f_hot.setInitialProfiles(n0=1e15)

# Enable the runaway electron grid
ds.runawaygrid.setEnabled(True)
ds.runawaygrid.setNr(50)
ds.runawaygrid.setNp(100)
ds.runawaygrid.setPmax(0.5)

# Set the advection interpolation method
ds.advectionInterpolation.setMethod(DREAM.AdvectionInterpolation.AD_INTERP_QUICK)

# Set the initialization method
ds.solver.setInitializationMethod(DREAM.Solver.INITIALIZATION_ISOTROPIC)

# Include fluid effects
ds.eqsys.f_hot.setInitialProfiles(n0=1e15)

# Set the time stepper
ds.timestep.setTmax(1e-1)
ds.timestep.setNt(20)

# Save the settings to an HDF5 file
ds.save('dream_settings.h5')
```

This code sets up a combined fluid-kinetic simulation using the DREAM library. It sets the electric field strength to 0.6 V/m, the electron density to 5e19 m^-3, and the temperature to 1e3 eV. It includes a fully ionized ion species named 'D' with a charge of 1. The hot-tail grid is disabled and the collision frequency mode is set to ultra-relativistic. The Dreicer and avalanche effects are included with the avalanche mode set to fluid and the Dreicer rate set to neural network. The initial profile is set to 1e15. If the runaway electron grid is enabled, it is set with 50 radial points, 100 momentum points, and a maximum momentum of 0.5. The advection interpolation method is set to use flux limiters and the initialization method is set to isotropic. The radial grid is set with a magnetic field strength of 5, a minor radius of 0.22, a wall radius of 0.22, and one radial point. The solver is set to nonlinear and verbose with a relative tolerance of 1e-4 for the runaway electron current density. The simulation includes fluid effects. The time stepper is set with a maximum time of 1e-1 and 20 time steps. The settings are saved to an HDF5 file named 'dream_settings.h5'. Source: assistant
EOT: true