In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.
Subject: Re: Inexpensive neutron source
Date: Oct 26, 8:46 am
Poster: Richard Hull
On Oct 26, 8:46 am, Richard Hull wrote:
>As with the Shoulder's experiments, there appears to be a distinct frequency range where electrons do very strange things to ions. In astro-physics, there are many anomalies reported in the "ion acoustic" range. Those hot clouds that astronomers see that radiate in this range are assumed to be shedding heat from a previous nova explosion but it could be possible that that they are still fusing catalytically because of the inteaction of the d ion and EV charge clusters, therby creating their own heat. At least that's the theory that I am pursuing.
Remember, there is such a thing as arc drop in a plasma. (old grizzled electronic engineers, such as yours turly, know this) You must...absolutely must, read the voltage directly across the tube and never across the supply (which is totally without value). High pressure gases are famous for never allowing even 100 volts to develop in plasma mode through their volume. Mercury vapor tubes rarely allow more than 13 volts. Neon which runs @ 5 torr (low pressure) rarely has 500 volts across the tube when running a 15kv tranformer. Thus the actual temperature of the plasma is many orders of magnitude lower than fusion temperature.
With RF input to the tube you will absolutely have to look at the voltage and current across the tube on a dual trace storage scope or you can't tell anything about what the plasma is doing. You will surely see that as the current rises the voltage falls off to near nothing and that as the voltage peaks, the tube is drawing almost no current.(plasma off).
Try running your tube with a good stiff 20kvdc supply and you will find you will burn the supply out or trip its breaker instantly.
This is why the neutron Fusor has to be run carefully and at relatively high vacuum. We need the rarification to allow the high potential to develop (fusion temperature) in the gas before the current runs away forcing all the voltage to reappear across the power supply limiters. This is also why a voltmeter in a power supply is often no good for fusor operation. The voltage across any would-be fusion device must be read at the terminal of the device containing the plasma.
A very long and extended "play" period with a demo fusor will bore this into the head quickly. This is why I so highly recommend a demo fusor as a first shot at the fusor effort.
Fusion success has a formula which I can't pull off my head just now, but it relates to confinement time and gas density. If you can get dense gases and confine for a long enough time you get superb fusion. The gas in the lamp you have is ultra dense, about 8 orders of magnitude denser than any fusor, but the voltage just can't be developed and held across the volume once in the plasma state. It would require almost infinite current and a source or supply impedance in the attohm range.(never happen)
While the fusor doesn't confine the plasma per se, it does have to maintain a steady voltage for acceleration between the electrodes of about 20 kvdc. This is a truly hot plasma condition for some few tens of thousands of lucky ions in the device each second.
In most supplies for such lamps as you have the RF is for excitation and there is actually a low voltage high current run engine backing this up.
In my average fusor run, I get no more than 50 to 100 times the back ground count. I find it incredible that a common deuterium lamp at high pressure driven by any supply on earth can bust the fusor performance by a full order of magnitude in neutron output. If so, most of these lamps can pose a significant neutron hazzard in use. I doubt this is the case.
Place a good geiger counter near the tube while running and see what you get.