More on operation - conditioning - data!
Posted: Thu Jul 07, 2016 4:32 pm
I am expecting a full operational visit for my fusor this weekend. It has not be run seriously since last October. I have to bring it back to life for this weekend.
In doing so, I took lots of data which I will not hash through, as I have done this in giant listings in prior years before the HEAS gathering in October. This is the norm here in the past as I brought the system back from a long sleep.
What I do want to iterate is related to my recent FAQ about operation and the roles of voltage, current and deuterium pressure.
viewtopic.php?f=24&t=10827
I wish to press on the issue of pressure in what follows.
Start up.......
I let my forepump run for about 30 minutes, pulling down the foreline, the diff pump and the chamber. (big gas load!) the foreline gauge near the forepump, which is a TC gauge, read 20 microns, while my capacitive manometer on the chamber read 15 microns. Needless to say, the manometer was the more accurate. I started the diff pump's fans and boiler and allowed it to run until the pressure on the manometer read 5e10-4 torr. (about another 20 minutes). I pinched off the chamber from the diff pump until the pressure rose only slightly (pretty close to complete shut off). I next opened the deuterium flow needle valve until the pressure leveled off at 12 microns. (flowing D2) I now opened the diff pump to fusor valve slightly until the pressure leveled off at 5 microns. (deuterium pressure)
The system was now ready for voltage. As I turned the voltage up, it lit off at about 15kv and 12ma. This is normal and one has to nurse the system from this point for a number of reasons. (Water load remaining and internal outgassing of the chamber, etc.) Slowly, the internal pressure drops as the gases other than deuterium are shuttled out via bombardment. After about one hour of this, I could put in a bit more gas and open the diff pump to fusor valve a bit more to maintain 5 microns and the process of measuring neutron number could begin. (second re-pressurization)
As the voltage crossed the 20kv range, the pressure continued to drop along with the current. Voltage could be raised to maintain the previous current. I tend to settle on maintaining a 10-12 ma current. Naturally, the neutron counts rose due to this effort. Stable operation can be achieved with this pressure fall, current fall and concommitent need for more voltage and higher neutron numbers.
The key thing is that I feel the pressure fall at this point is due to burying of deuterium in the chamber walls. At higher voltages and the same maintained current, (more power is placed into the system), I feel more and more deuterium is buried and this aids the fusion returns for many reasons I have posited in the past. This remains my theory. I have been doing this for years now, perhaps longer than anyone with a working fusor.
Setting my theory aside, here is a tiny fraction of the data I have taken.
Second repressurization to 5 microns of D2
29kv at a fallen pressure of 3.8 microns @ 9ma 2050 n/s
33kv at 3.7 microns @ 10 ma 3800 n/s
35.2 kv at 3.6 microns @ 11.5 ma 5106 n/s
Third repressurization to 5.4 microns of D2
22kv at 5.4 microns @ 10ma 1981 n/s
25kv at 5.0 microns @10.1 ma 4854 n/s
29kv at 4.9 microns @10 ma 10,161 n/s
35kv at 4.8 microns @9.5ma 24,732 n/s
We see a nearly 5 fold increase at 35kv @ 10ma between the two runs due to an increase in D2 pressure of only 1.2 microns!!!
Thanks are due to the larger, efficient 3He tube which allows for very fine data collection at low numbers due to its providing a torrent of counts over other neutron counting systems. All of this with no regard or need for any form of statistics. My background count over 3 ten minute runs was 9 cpm. At only 15kv 5microns @ 10ma I was getting 32 cpm. Doing real fusion outside of any statisitics and making about 600n/s.
Pressure is obviously king here at any givien voltage and current. Perhaps un-burying of what becomes deuterons at the shell's surface allow for full acceleration over the potential gradient. (this is a key proposition in my use of the phrase "fusor conditioning") In short, the shell seems to be acting as a grossly irregular and inefficient ion source operating over a huge surface area. Whats more, the ions are created at the ideal point, near the shell amidst a hail of infalling electrons!
There may be a balance point in fusor size! Get as much surface area as possible to take advantage of this process, but not so large in radius that there is little likelihood of the shell produced deuteron's mean free path increasing to the point that they fail to make the grid. There is much to consider here. Hydrogen loves to insinuate itself into metals...all metals. It can be stuffed in to the lattice any number of ways and re-released, also, in any number of ways.
Even the meanest intelligence can see what the same voltages and current can do at a pressure increase differential of only 1.6 to 2 microns!
So it is not all about voltage and current or even power! Arm yourself with 90kv @ 100ma and unless you can get a good deuterium atmosphere pressure in the chamber you are whistling in the wind. You will have impressive stuff, but might not do good fusion in your fusor. Can you have too much operational pressure in a fusor? All of the mega mark results have been at high pressure. (>10 microns+) It seems that if you can get the voltage and current into the fusor, pressure is the limiting factor.
This goes back to my postings saying it is operational experience, years of it, that can tell the tale and make the difference in resultant fusor performance.
Can a discussion begin here relating to pressure by old hands who read this? I have put forth data and a few theoretical musings related to "conditioning".
Richard Hull
In doing so, I took lots of data which I will not hash through, as I have done this in giant listings in prior years before the HEAS gathering in October. This is the norm here in the past as I brought the system back from a long sleep.
What I do want to iterate is related to my recent FAQ about operation and the roles of voltage, current and deuterium pressure.
viewtopic.php?f=24&t=10827
I wish to press on the issue of pressure in what follows.
Start up.......
I let my forepump run for about 30 minutes, pulling down the foreline, the diff pump and the chamber. (big gas load!) the foreline gauge near the forepump, which is a TC gauge, read 20 microns, while my capacitive manometer on the chamber read 15 microns. Needless to say, the manometer was the more accurate. I started the diff pump's fans and boiler and allowed it to run until the pressure on the manometer read 5e10-4 torr. (about another 20 minutes). I pinched off the chamber from the diff pump until the pressure rose only slightly (pretty close to complete shut off). I next opened the deuterium flow needle valve until the pressure leveled off at 12 microns. (flowing D2) I now opened the diff pump to fusor valve slightly until the pressure leveled off at 5 microns. (deuterium pressure)
The system was now ready for voltage. As I turned the voltage up, it lit off at about 15kv and 12ma. This is normal and one has to nurse the system from this point for a number of reasons. (Water load remaining and internal outgassing of the chamber, etc.) Slowly, the internal pressure drops as the gases other than deuterium are shuttled out via bombardment. After about one hour of this, I could put in a bit more gas and open the diff pump to fusor valve a bit more to maintain 5 microns and the process of measuring neutron number could begin. (second re-pressurization)
As the voltage crossed the 20kv range, the pressure continued to drop along with the current. Voltage could be raised to maintain the previous current. I tend to settle on maintaining a 10-12 ma current. Naturally, the neutron counts rose due to this effort. Stable operation can be achieved with this pressure fall, current fall and concommitent need for more voltage and higher neutron numbers.
The key thing is that I feel the pressure fall at this point is due to burying of deuterium in the chamber walls. At higher voltages and the same maintained current, (more power is placed into the system), I feel more and more deuterium is buried and this aids the fusion returns for many reasons I have posited in the past. This remains my theory. I have been doing this for years now, perhaps longer than anyone with a working fusor.
Setting my theory aside, here is a tiny fraction of the data I have taken.
Second repressurization to 5 microns of D2
29kv at a fallen pressure of 3.8 microns @ 9ma 2050 n/s
33kv at 3.7 microns @ 10 ma 3800 n/s
35.2 kv at 3.6 microns @ 11.5 ma 5106 n/s
Third repressurization to 5.4 microns of D2
22kv at 5.4 microns @ 10ma 1981 n/s
25kv at 5.0 microns @10.1 ma 4854 n/s
29kv at 4.9 microns @10 ma 10,161 n/s
35kv at 4.8 microns @9.5ma 24,732 n/s
We see a nearly 5 fold increase at 35kv @ 10ma between the two runs due to an increase in D2 pressure of only 1.2 microns!!!
Thanks are due to the larger, efficient 3He tube which allows for very fine data collection at low numbers due to its providing a torrent of counts over other neutron counting systems. All of this with no regard or need for any form of statistics. My background count over 3 ten minute runs was 9 cpm. At only 15kv 5microns @ 10ma I was getting 32 cpm. Doing real fusion outside of any statisitics and making about 600n/s.
Pressure is obviously king here at any givien voltage and current. Perhaps un-burying of what becomes deuterons at the shell's surface allow for full acceleration over the potential gradient. (this is a key proposition in my use of the phrase "fusor conditioning") In short, the shell seems to be acting as a grossly irregular and inefficient ion source operating over a huge surface area. Whats more, the ions are created at the ideal point, near the shell amidst a hail of infalling electrons!
There may be a balance point in fusor size! Get as much surface area as possible to take advantage of this process, but not so large in radius that there is little likelihood of the shell produced deuteron's mean free path increasing to the point that they fail to make the grid. There is much to consider here. Hydrogen loves to insinuate itself into metals...all metals. It can be stuffed in to the lattice any number of ways and re-released, also, in any number of ways.
Even the meanest intelligence can see what the same voltages and current can do at a pressure increase differential of only 1.6 to 2 microns!
So it is not all about voltage and current or even power! Arm yourself with 90kv @ 100ma and unless you can get a good deuterium atmosphere pressure in the chamber you are whistling in the wind. You will have impressive stuff, but might not do good fusion in your fusor. Can you have too much operational pressure in a fusor? All of the mega mark results have been at high pressure. (>10 microns+) It seems that if you can get the voltage and current into the fusor, pressure is the limiting factor.
This goes back to my postings saying it is operational experience, years of it, that can tell the tale and make the difference in resultant fusor performance.
Can a discussion begin here relating to pressure by old hands who read this? I have put forth data and a few theoretical musings related to "conditioning".
Richard Hull