PlasmaPhase electron enthalpy depends on gas temperature

[speth]

Problem description

The enthalpy of the electron species in PlasmaPhase is calculated incorrectly, such that the enthalpy of the electron depends on both the electron temperature and the temperature of the non-electron species. This appears to be a result of calculating the non-dimensional enthalpy using the electron temperature in the overridden updateThermo method, but then dimensionalizing it using the gas temperature in IdealGasPhase::getPartialMolarEnthalpies (which is not overridden).

Steps to reproduce

>>>[1]: import cantera as ct
>>>[2]: p = ct.Solution('test/data/oxygen-plasma.yaml',
                        'discretized-electron-energy-plasma', transport_model='None')
>>>[3]: p.TPX = 300, 101325, 'E: 1'
>>>[4]: p.Te
379740.6337340625
>>>[5]: p.enthalpy_mole
6230904.132044763
>>>[6]: p.TP = 301, None
>>>[7]: p.enthalpy_mole
6251673.8124849135
>>>[8]: p.Te
379740.6337340625

Behavior

The molar enthalpy for a phase of pure electrons should only depend on Te, not T.

System information

• Cantera version: 2.6.0 or main at 8fbb4bc

Attachments

Additional context

This was discovered as part of #1299, which implements Cantera/enhancements#114.

[BangShiuh]

I think some system thermodynamic parameter might not be applicable for plasma. Ex. G = H - T S. But for convenience, it might be good to have a option to neglect the contribution of electron so that the system thermodynamics can still be obtained.

[speth]

Yes, you're right, some of the bulk properties will not satisfy those relationships when the electron temperature is different from the gas species, but I think at least g_electron = h_electron - T_electron * s_electron should still be true.

[ischoegl]

Fixed by #1323