If the Papp cylinder is really a form of pulse power capacitor...
You're not multiplying entities beyond necessity, you're multiplying entities in order to add an inferior mechanism.
The plasmoid is all that is needed to:
1) Explain the mechanical motion of the piston,
and
2) Explain the energy storage mechanism inside the cylinder.
The plasmoid energy storage is magnetic pressure. The piston movement is from magnet pressure. The very fast rise time of the discharge is from the collapse of the magnetic field.
Capacitor discharge doesn't want to have fast rise times. Inductive collapse of magnetic fields can't help but have fast rise times.
Stop fighting mother nature and complicating things, Axil.
Jabowery thanks for your interest in this subject.
The plasmoid energy storage is magnetic pressure. The piston movement is from magnet pressure. The very fast rise time of the discharge is from the collapse of the magnetic field.
This assertion sounds true but can be proven experimentally by using a non-magnetic material like stainless steel or plastic to form the piston.
Capacitor discharge doesn't want to have fast rise times. Inductive collapse of magnetic fields can't help but have fast rise times.
You have missed the key to how the Papp engine works. Capacitive discharge from the noble gas mix is where the Papp engine gets the power to produce the spark discharge. It is collected by the buckets and passed directly to the electrodes in the other cyclinder and it flow is timed by a distributor.
In order to produce high energy EMF like UV and x-rays the spark discharge needs to also be more energetic.
Without Alpha emitters, a 40kv spark discharge that Papp used might just not be strong enough to do this job. This voltage is even below most of the x-ray residence levels produced by tungsten.

Bremsstrahlung and characteristic radiation spectra are shown for a tungsten anode with x-ray tube operation at 80, 100, 120, and 140 kVp and equal tube current.
Furthermore, Papp used Alpha emitters catalyzed by spark discharge as the main source of x-rays. A modern Papp engine design cannot use powerful Alpha emitters like radium. So a very high energy plasmoid is required to compensate for the lack of alpha radiation and the low spark level that Papp used.
A high powered plasmoid will generate those twisting large magnetic fields that you describe. These fields will accelerate electrons to very high energy levels. These electrons will in turn produce the x-rays that are so important in the Papp engine.
Subject to experimentation, the Papp engine must be gainful. X-rays of sufficient power might provide over unity ionization in noble gases since Papp depended on X-ray production in his design to be gainful.
More self-generating power is required from the noble gas mix via x-ray production in the current Papp design to compensate for the removal of radioactive sources from the 1984 design.
That means move voltage coming out of the noble gas mix. This is where capacitive discharge comes into play.
Please disabuse me any defects in thinking as has been done by others here often.