With Regards to Abd ul-Rahman Lomax comment on pre-ionization…
The Papp reaction is hard to get a handle on because Papp produced two patents with multiple “Preferred Embodiments.”
Having stated this declaimer up front, as far as I can tell at this juncture, Papp used alpha particle emitting radioactive isotopes to produce accelerated alpha emissions when directly exposed to a strong spark discharge.
Papp states that this nuclear based sub-reaction generates x-rays that produce the pre-ionization. Note in the Papp patent: The cathode and anode carry the radioactive isotopes.
From the US Patent # 4,428,193 (January 31, 1984)
“the gating signal supplied from distributor 135 to unit 121 is also supplied to relay 97A. The current from switching unit 121 and from oscillator 95 also is supplied to the anode and the cathode. It is calculated that this causes radioactive rays (x-rays) to flow between the anode and the cathode, thereby further exciting the gaseous mixture.”
As far as I know, this is on the fringe of nuclear science and in fact may not be valid; a science fantasy that Papp invented.
Even if this unorthodox use of alpha emission were valid, there are better ways to pre-ionize the spark channel that has been devised since the 80’s. This technique is commonly used in plasmoid generators and nuclear space ion thrusters.
This is done by producing x-ray and UV-ray photons, and high energy electrons by simply applying a high voltage pre- spark discharge to condition the primary spark channel to ionize the gas in the small gas filled space between the electrodes.
As a practical matter, a commercial Papp engine cannot use large amounts of radio-active isotopes to support the Papp this type of nuclear reaction. There is a 4 ounce limit on possession of Th232 imposed by the Nuclear Regulatory Commission (NRC) to thwart the construction of the U233 bomb.
Yes, it would be interesting to experimentally verify that exposing alpha emitters to a spark discharge will produce gas ionizing X-Rays, but it does not further the development of the Papp engine under the current nuclear regulatory environment.
By the way, check out the case study on David Hahn as an object lession for all those who deal in excessive and inappropreate use of radioactive sources.
http://en.wikipedia.org/wiki/David_Hahn“On August 1, 2007, Hahn was arrested in Clinton Township, Michigan for larceny, in relation to a matter involving several smoke detectors, allegedly removed from the halls of his apartment building. In his mug shot, his face is covered with sores which investigators claim are possibly from exposure to radioactive materials. During a Circuit Court hearing, Hahn pleaded guilty to attempted larceny of a building. The court’s online docket said prosecutors recommended that he be sentenced to time served and enter an inpatient treatment facility. Under terms of the plea, the original charge of larceny of a building would be dismissed at sentencing, scheduled for October 4. He was sentenced to 90 days in jail for attempted larceny. Court records stated that his sentence would be delayed by six months while Hahn underwent medical treatment."

Cross posted on vortex.