Successful fusion in my fusor - Neutron detection!
Posted: Sun Feb 19, 2017 2:47 pm
Well, after a number of setbacks, even as late as yesterday, this afternoon I obtained significant neutron signals from my Russian made boron detector tube (a SNMO-5 NOS) using my fusor.
For the data obtained for each fusor run (with a moderator) I detected an average of 640 counts/min with the fusor's average operating current of 36 ma @ 31 kV and 6.5 microns of pressure of deuterium gas (this pressure parameter was not changed during any of the runs.) The average reading with no moderator was 38 counts (fusor still running at rated power, of course.)
I performed a total of ten runs each for 60 seconds of duration (then the counter was stopped); also, for the total number of data sets (10) the highest and lowest data set pairs were thrown out of the data set (so I only used eight runs (each with and without the moderator) for this average. Aside: the two extreme runs deleted from the data set would have slightly raised my total counts for neutrons but decreased the non-moderator count.)
I had a lead shield of 7.5 mm thickness besides the steel fusor case (3-4 mm thick (guess)) between the detector and fusor.
The moderator was 10 cm total made of paraffin.
My lecture bottle of deuterium is 99.8% pure; I used a fine needle valve to control the pressure after the gate valve for the diffusion pump was nearly closed. My Cathode is a hand bent 'cage' made of steel wire 3.5 mm thick (a high temp steel alloy welding rod.)
The detector was located 25 cm from the center of the fusor (to the center of the detector.) The moderator was between the detector and center of the fusor. This is a typical Russian Boron based tube - 30 cm long, about 3.5 cm diameter; I encased the detector in a 2.5 mm wall thickness copper tube that electrically shielded the detector to help exclude electrical interference. The detector was connected via a high voltage coaxial cable (7 ft long) to a 3-way connector (for the power and counter coaxial cables.) The detector voltage was 1.99 kV with a 50 Mega-ohm resistor (between the x-former and coaxial connector.) I used a Spectech ST-360 counter unit (connected to its scintillation input.) The Russian neutron detector tube is a SNMO-5 NOS; w/natural counter background of: 0.034; the min. operating voltage 1.9 kV. The ST-360 counter is also powered by the 12 volt car battery battery via a std 120 volt inverter; this inverter's 120 VAC output also provided power to the variac (that varied the voltage to the 5 kV DC transformer to 1.99 kV pos. DC.) The signal from the neutron detector (no fusor; all other power sources off except for the detector supply) was 2 counts per ten minutes (I assume this was caused by the PS on, then off cycle to the detector.)
The runs were as follows:
A fusor run with detector behind the lead shielding and with 10 cm of paraffin. Then the moderator was removed for a noise run (full plasma operation at typical fusion current/voltage.) This was done ten times for one minute duration for each condition (the reading was blind - I only monitored the time, not counts until after the run was done. Only then did I select and read the count number on the ST-360.) The counter was reset each time to zero. Once I ran the full fusor system (moderator in place) at just 19 kV, 30 ma with plasma for a null test to make sure fusor noise was not a major issue (see data for the null test, below.)
Data (all are for 60 sec duration):
Data Runs (Feb 19,2017; around 1:00 PM)
Counts with moderator / Counts with no moderator
(Conditions: Fusor voltage 30 kV and 32-34 ma current)
1454 / 28
501 / 44
461 / 63
429 / 31
705 / 81
The voltage increased to 31 kV and current increased to 35 -38 ma
625 / 36
(here the current increased again to 42-44 ma and voltage was 31/32 kV (max. value for my PS)
1377 / 45
1184 / 60
I had to stop due to the chamber becoming overly hot (turns out my D2 feed line (made of teflon) was melting. The line, fortuitously, did not fail.)
The null run had a count of 26 (for 60 sec.) Moderator in place, detector running but the fusor was operated at 19 kV/30 ma so no fusion was occuring (but I would have a significant power in the plasma.)
The star mode was clear and the system ran nearly flawless - rock steady except for a slow increase in current that was hard to prevent. The pressure remained constant for all runs @ 6.5 microns.
I am asking for this to be considered for evaluation.
Thank you all for all the help and suggestions over the years to get me to this point!
For the data obtained for each fusor run (with a moderator) I detected an average of 640 counts/min with the fusor's average operating current of 36 ma @ 31 kV and 6.5 microns of pressure of deuterium gas (this pressure parameter was not changed during any of the runs.) The average reading with no moderator was 38 counts (fusor still running at rated power, of course.)
I performed a total of ten runs each for 60 seconds of duration (then the counter was stopped); also, for the total number of data sets (10) the highest and lowest data set pairs were thrown out of the data set (so I only used eight runs (each with and without the moderator) for this average. Aside: the two extreme runs deleted from the data set would have slightly raised my total counts for neutrons but decreased the non-moderator count.)
I had a lead shield of 7.5 mm thickness besides the steel fusor case (3-4 mm thick (guess)) between the detector and fusor.
The moderator was 10 cm total made of paraffin.
My lecture bottle of deuterium is 99.8% pure; I used a fine needle valve to control the pressure after the gate valve for the diffusion pump was nearly closed. My Cathode is a hand bent 'cage' made of steel wire 3.5 mm thick (a high temp steel alloy welding rod.)
The detector was located 25 cm from the center of the fusor (to the center of the detector.) The moderator was between the detector and center of the fusor. This is a typical Russian Boron based tube - 30 cm long, about 3.5 cm diameter; I encased the detector in a 2.5 mm wall thickness copper tube that electrically shielded the detector to help exclude electrical interference. The detector was connected via a high voltage coaxial cable (7 ft long) to a 3-way connector (for the power and counter coaxial cables.) The detector voltage was 1.99 kV with a 50 Mega-ohm resistor (between the x-former and coaxial connector.) I used a Spectech ST-360 counter unit (connected to its scintillation input.) The Russian neutron detector tube is a SNMO-5 NOS; w/natural counter background of: 0.034; the min. operating voltage 1.9 kV. The ST-360 counter is also powered by the 12 volt car battery battery via a std 120 volt inverter; this inverter's 120 VAC output also provided power to the variac (that varied the voltage to the 5 kV DC transformer to 1.99 kV pos. DC.) The signal from the neutron detector (no fusor; all other power sources off except for the detector supply) was 2 counts per ten minutes (I assume this was caused by the PS on, then off cycle to the detector.)
The runs were as follows:
A fusor run with detector behind the lead shielding and with 10 cm of paraffin. Then the moderator was removed for a noise run (full plasma operation at typical fusion current/voltage.) This was done ten times for one minute duration for each condition (the reading was blind - I only monitored the time, not counts until after the run was done. Only then did I select and read the count number on the ST-360.) The counter was reset each time to zero. Once I ran the full fusor system (moderator in place) at just 19 kV, 30 ma with plasma for a null test to make sure fusor noise was not a major issue (see data for the null test, below.)
Data (all are for 60 sec duration):
Data Runs (Feb 19,2017; around 1:00 PM)
Counts with moderator / Counts with no moderator
(Conditions: Fusor voltage 30 kV and 32-34 ma current)
1454 / 28
501 / 44
461 / 63
429 / 31
705 / 81
The voltage increased to 31 kV and current increased to 35 -38 ma
625 / 36
(here the current increased again to 42-44 ma and voltage was 31/32 kV (max. value for my PS)
1377 / 45
1184 / 60
I had to stop due to the chamber becoming overly hot (turns out my D2 feed line (made of teflon) was melting. The line, fortuitously, did not fail.)
The null run had a count of 26 (for 60 sec.) Moderator in place, detector running but the fusor was operated at 19 kV/30 ma so no fusion was occuring (but I would have a significant power in the plasma.)
The star mode was clear and the system ran nearly flawless - rock steady except for a slow increase in current that was hard to prevent. The pressure remained constant for all runs @ 6.5 microns.
I am asking for this to be considered for evaluation.
Thank you all for all the help and suggestions over the years to get me to this point!