Archived - New Jersey: KR-2 12" Fusor

[ericstroud]

Hi everyone! It’s been a long time since I’ve talked with some of you at HEAS 2007 and even longer since I’ve posted. Things have been hopping up here in the NJ/NY Metro area in the past year.

I give you: KUGELREAKTOR-2 (KR-2). This fusor is built for Helium-3 work, which will probably be done outdoors and far away from the operator! I will post more on the He3 attempts as this summer goes on.

Details/Specifications as follows to support the pictures:

Chamber:
Steel, 12” diameter and spherical, courtesy of George, K0FF. If has seven (7) ports arranged equatorially. Six ports are 2.75” CF, except the center port which is utilized as a 3-3/8” viewport. At top is an 8” CF Varian HV 50kV feedthrough with a ¼” stalk, insulated with alumina ceramic tubing. The chamber base is a 6” CF. All copper gaskets were used on the chamber. A Stirling cryocooler can be seen at the right of the gate valve, attached to the chamber shell to assist in cooling if needed. Three conflats are blanked off at present. One is reserved for a Canberra PIPS detector once I figure out how to mount it to a 2.75” CF with a copper gasket. I am wearing a lead apron in one picture, using my hand as a reference for the chamber size.

High Conductance Vacuum system
Roughing: Trivac D8A to a Lesker Micromaze with KF isolation valves.
High Vacuum: Edwards SI-100 diffusion pump with peltier-cooled baffle, manual gate valve to chamber.
Meters: Roughing is monitored by a Varian 815 thermocouple gauge. Chamber is monitored with a Varian hot cathode gauge and an MKS 722A11TGA2FJ 10-torr Baratron. The controller for the HCG automatically switches off the filament voltage once vacuum above 10-4 mmHg is attained. A manual 6” gate valve is between the chamber and diffusion pump baffle.

High Voltage
High voltage is a homebrew system consisting of a large X-ray transformer in silicone oil, placed in a metal drum. The secondary is fed through a large Memcor 840 1500-ohm wirewound ballast resistor before connecting to the feedthrough. Control is via a HUGE General Radio 7kVa variac, courtesy of Richard Hull at HEAS 2007! Secondary voltage is monitored through a large IRC 100-meg tigerstripe you see zip-tied to the ballast resistor. Safety interlock and meters are via a 20’ power cable, laying on the floor.

Grid
To support D2 fusion, a triple loop, 99.9% tungsten 0.25mm wire is currently in the chamber and photos. The grid was constructed as per Jon Rosenstiel’s method. Loop diameter is 1.5 inches. This will be replaced with a solid grid as we get the He3 ball rolling. This gives about an 8:1 ratio of chamber diameter to grid diameter.

Fuels
Deuterium and He-3 are on hand. I’m manually metering a gas using Swagelok/Nupro metering valves. In order to do the D2-He3 reaction, molar gas ratios must be precisely controlled. I have one surplus Precision-10 Cole-Parmer programmable mass flow controller on hand with H2 and He in its menu selections, but I really need the second to do serious work. More pics later.

Neutron Metrology
Snoopy NP2 and bubble detectors, BUT, my bubble detectors are over a year old and kaput! One leaks gel, the other does not suppress all of the bubbles upon tightening to the maximum position (seen in picture). Three news ones have been ordered and shipped this week, so I will follow up this post with those pictures in June when they arrive as proper evidence.

A few operational notes
All CF bolts were set with a torque wrench, and that took a long time! I gave this chamber a long pump down and glow discharge cleaning. Wanting to ensure that a clean vacuum was attained before trying D2 work, I was pleased to see just about 10-6 mmHg according to the HCG. Secondary is at approximately 33-34kV, 7mA in these pics. Note the tungsten grid starting to glow red. The ballast resistor really helps to stabilize the plasma. The outer shell is barely warm during ten-minutes of operation, precluding the use of the Stirling cryocooler. The star mode is in the same plane as the viewport. In hindsight, I should have used a HV feedthrough on an equatorial port instead of the top port – It may have made for better star pictures.

In closing, I’ll definitely post updates once the new bubble dosimeters arrive to confirm evidence of the D2 reaction. I’m looking forward to many discussions with you all. As a chemist, I have a learning curve ahead of me for sure! Enjoy the holiday weekend. Kindest regards, Eric

[Mike Beauford]

Very nice setup indeed! I'm turning green over here!

Mike

[Jon Rosenstiel]

Hi Eric,

I’ll third that… nice setup! Thanks for the photos and detailed progress report. Kinda’ funny, earlier this week I was thinking about you and your fusor project.

Yeah, the BTI’s are kind of fussy, their "half-life" is rather short, and they definitely don’t like temperature extremes.

Jon R

[tolson1118]

Very nice setup!
How high do you hope to run your voltage?
As you'll be using 3He. which has a higher cross section at rather high KeV values.
I look forward to seeing your results!

-Thiago

[ericstroud]

Hi Everyone-
Thanks for the kind words!

Thiago - I'm pretty sure I could approach 100kv out of that xray transformer in oil if I had to, before the diodes pop or something catastropic happens . I feel confident about operating in the the 50-60kv range, given the type of secondary wiring and insulator size. Above that, I will have to adopt Carl Willis' fluid/acrylic design to increase the insulation poperties around the feedthrough. The resulting x-ray issues are why I'm thinking of putting the unit outdoors and far away from the operator position.

Kind regards, Eric

[Steven Sesselmann]

Erik,

Must have missed your post the first time around, this is really impressive, well done.

I look forward to adding the Kugelreaktor to my Q list, when you get some fusion data.

Steven

[Carl Willis]

Hi Eric,

Beautiful contraption there.

I had my eye on that Peltier-baffled diff pump on eBay a couple months ago as well. What kind of fluid did you put in it?

The He-3 experiments should be interesting.

-Carl

[ericstroud]

Hi Carl-

The spec calls for 20mL. I used MT-704 fluid from Specialty Fluids (tetramethyltetraphenyltrisiloxane), which was desirable from a cost perspective.

Kind regards, Eric

[Richard Hull]

Eric, Great work! I have added you to the plasma club. I would do D-D fusion first to get on the Neutron club. Later, if you get D-He3 fusion, I will suffix to your name, first to do D-He3 fusion.

All the best of luck.

Richard Hull

[ericstroud]

Hi everyone-

Bubble detectors arrived! Here's is the result of exactly a 10-minute D+D run (10 microns, 31kV, 6ma). Detector was placed ontop of a conflat flange close to the shell. I didn't experience any dramatic warming of the shell during operation. From this position to the center of the poissor, let's call the radius 6.5 inches.

Kind regards, Eric

[Steven Sesselmann]

Eric,

Congratulations and well done.

The efficiency will no doubt improve as impurities are pumped out of the system. I take it that this is a trial run and that you will soon show us more bubbles

[edited 06/04/08]

Cathode potential 31 kV
Current input 6 mA
Bubble count 2 Bubbles
Bubbles/mrem (calibration) 20
Detector distance 17 cm
Exposure time 600 s
Supp power - Ion guns etc. 0 Watt

Power input 186 Watt
Neutron flux at detector 4.68E+00 n/s/cm^2
Neutrons isotropic 1.60E+04 n/s
Total D+D fusion reactions 32022.37958 fusions/s

Proton 41.4 8.07E-09
Neutron 33.6 6.55E-09
Triton 13.8 2.69E-09
Alpha particle 11.2 2.18E-09

Total fusion power 100.0 1.95E-08

Steven

[ericstroud]

Hi Steve -
Many thanks for doing the Q calculation! I was curious about the 33 bubbles/rem constant. On this new batch of dosimeters, each has a calibration value, all are different.

On the particular detector shown in this picture (and used for the POC run), the label value is 20 b/mrem (1.9 b/uSv). Should that be adjusted in the Q calculation?

Kind regards, Eric

[Steven Sesselmann]

Eric,

Sorry, I couldnt read the calibration sticker, so I assumed it was a 33 bmr, I will do the calc again and edit the above post.

Steven