Fusion Message Board

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: Gas densities, tritium production
Date: Apr 08, 6:34 pm
Poster: Richard Hull

On Apr 08, 6:34 pm, Richard Hull wrote:

Well guys.....

I did the post on statistics in those dead moments after work between 5 and 6 pm EST.

As I drove home, self satisfied with the nice statistical bombast presented, I realized that when I am really feeling, self satisfied and at the top of my form, I have undoubtedly screwed up!

During those reflective moments driving home, I realized a major error, but it will impact only part of the post.


Statistical computation #2 is fulla' beans!!!!


The 10 ma current is an actually an electron current ONLY!!!

Think about it!

The whole business is designed to emit electrons via field emission from the inner grid and these are to create deuterons via collision, etc in the inter grid region as they streak towards the huge positive spherical chamber wall.

Also what the heck heats the chamber walls to over 100 degrees above ambient?!!! Stupid, stupid, DUH!

It is electrons and electrons only!

By simple physics, not one deuteron or ion in the entire chamber can ever touch the outer shell!!!!!!

Also, I forgot a basic, but little touted axiom. Mean free paths of electrons at any given pressure are tremendously greater than gas ions (deuterons).

Thus, in statistical statement #2 I must say that we are creating about 10e17 electrons/second not deuterons. Now what else does this impact and how many deuterons are we makin'!?

Well, we can assume that the mean free path for the electrons at 1 micron in deuterium is over two meters!!!!! This means that in the small 3"inter grid region, an electron hitting a deuterium gas molecule and ionizing to a deuteron is going to be a statistically rare event!!!!

Assumption and calc time again boys and girls.

With a four meter sphere of deuterium absorbing about half of all electrons in collision (mean free path)....that means we would only consume about 5X10e16 electrons in a volume of 33,500,000cc! as our chamber is only 1850cc that means that .000055 of the above number of electrons would stop and do work in our chamber!!

Therefore we might reasonably expect about 2.75x10e12 deuterons to be made per second in the volume of our chamber. Down by a factor of 100,000 from the number originally predicted in this post. Thus for every 100,000 electrons blasting towards the outer wall only one makes a deuteron! This means an actual deuteron current of only 100 nanoamps flowing in the direction of the inner grid.

What else have I screwed up?!

Well #5 recalc'd from the above shows that we are now only ionizing to deuterons about 1/10,000th part of the total deuterium gas load! OOPS!

This means a wonderful boost for efficiency of deuteron production versus neutron production!
instead of one neutron per trillion deuterons it is now one neutron per 10 million deuterons (Again, that 100,000 factor, but this time a welcome increase in efficiency to .00001% efficiency. Unfortunately the electrical power in to neutron production effcieincy remains at .00000000001%.

Another way of putting it is that 100,000 times more power goes into heating the chamber walls via electron collisions than goes to the production of deuterons or that we pour in 1 trillion times more power to heat the walls as is produced in actual neutrons!

Think of your fusor as a super efficient space heater which, as a microscopic waste product, dribbles out neutrons and outerspace vacuum levels of tritium and helium3.

This is humourous to me and shows why that chamber gets so darned hot. I have burned myself on mine a couple of times. At 25kv @10 ma that is 250 watts of input energy and of that we can expect about .000000000001 watts of neutron energy added.
As Scott says on his webb site. This thing is indeed over unity!!!

Forget internal gas molecular heating of the walls as at 1 micron, there just ain't no real conduction of heat in the gas. That is why your TC gauge peters out in that region. There is probably much more radiant heating of the walls from the dense hot poissor within the inner grid than heat conduction through the gas!

No, Virginia, this thing is electronically heated. and we are actually over unity by ~10 picowatts.

Richard Hull