The long awaited 1.33" Fusor construction write up.
Posted: Mon Feb 25, 2013 7:37 pm
The following are the images of the entire process of building the Fusor followed by plasma pictures. All mounting hardware is 316SS plated in 99.999% Silver to act as lubricant, the only exception is the MD5 leak valve which was lubricated with KJLC brand anti-sieze lubrication for threads.
Photo:
1.) This first image is of the main chamber. From wall to center of the cube it is .67", this 6-way cube was manufactured by KJLC out of their standard vacuum chamber stainless steel. The fittings on the chamber are 1.33"CF flanged with 8-32 x .5" tapped holes.
2.) This is an image of the MD5 series leak valve that also acts as the fore line valve between the chamber and roughing pump. This valve is capable of doubling as a leak free shut off valve as well, it can have a controlled leak down to 10^-7 Torr but will work as a shut off valve down to 10^-11 with a leak rate of 10^-12. I used this because I can basically use it as a flow control for the pump because of the small chamber size. The construction is all SS with a stellite knife edge and nickel diaphragm.
3.) This is a 1.33" close coupler provided by Kimball Physics, this part is used to join two tapped cf flanges of the same size. The coupler is needed to attach the MD5 leak valve to the chamber with minimal foot print. The holes are off set thus allowing access of a hex wrench. Standard SS construction.
4.) These are the two hemispheres of the grid before trimming of the excess materials. These are two evaporation filaments made out of Tungsten wire with a thickness of .092" by KJLC. There are many reasons for using two spiral hemispheres that are outlined in the grid assembly photo. After machining these filaments were cleaned in acetone followed by Isopropanol to ensure no particle contamination within the chamber.
5-6.) These two photos are of the completed inner Grid construction, as you can see they are attached to the feedthrough wires with inline barrel connectors constructed with BeCu and SS316 screws provided by KJLC. This two hemisphere design was chosen for a number of reasons, the first being any grid I could think of is too large to fit into the small hole of the chamber thus calling for a design that can be compressed then decompressed once inside the chamber, the second being with these two separately insulated grids it allows the ability to attach two AC leads as well as connecting a single DC lead, and the third would be the ease of precision construction in a small time frame. This grid can be replaced within a matter of minutes with a minimal amount of construction. The two ends of the conical filament fits perfectly into the ports of the 6-way cube. I am possibly switching to a more substantial feedthrough due to the fact that there is slight arcing at lower pressures. In spite of this, the design will remain the same except for the external dimensions of the feedthrough.
7.) This shows the grid installed along with the D2 gas feedthrough. This D2 gas feedthrough is all 1/4" swage-lok port connectors and elbows constructed out of SS. As shown, the grid tolerances are small but the fit is immaculate within the chamber allowing a relatively good amount of space to spare.
8.) This is the chamber with: the MD5 valve, power feedthrough, close coupling, D2 inlet, and a blank flange on the opposite side of the chamber behind the grid.
9.) This is the final product with the Lead glass viewport installed along with the second blank flange and 2.75"-1.33" conical reducer in the bottom of the image. This reducer (SS) is used to attach to the Turbo and roughing pump system.
10.) This is the first AC plasma out of the machine. This was created with an NST 15kv@30ma at around 80mbar.
Thank you for your patience.
Photo:
1.) This first image is of the main chamber. From wall to center of the cube it is .67", this 6-way cube was manufactured by KJLC out of their standard vacuum chamber stainless steel. The fittings on the chamber are 1.33"CF flanged with 8-32 x .5" tapped holes.
2.) This is an image of the MD5 series leak valve that also acts as the fore line valve between the chamber and roughing pump. This valve is capable of doubling as a leak free shut off valve as well, it can have a controlled leak down to 10^-7 Torr but will work as a shut off valve down to 10^-11 with a leak rate of 10^-12. I used this because I can basically use it as a flow control for the pump because of the small chamber size. The construction is all SS with a stellite knife edge and nickel diaphragm.
3.) This is a 1.33" close coupler provided by Kimball Physics, this part is used to join two tapped cf flanges of the same size. The coupler is needed to attach the MD5 leak valve to the chamber with minimal foot print. The holes are off set thus allowing access of a hex wrench. Standard SS construction.
4.) These are the two hemispheres of the grid before trimming of the excess materials. These are two evaporation filaments made out of Tungsten wire with a thickness of .092" by KJLC. There are many reasons for using two spiral hemispheres that are outlined in the grid assembly photo. After machining these filaments were cleaned in acetone followed by Isopropanol to ensure no particle contamination within the chamber.
5-6.) These two photos are of the completed inner Grid construction, as you can see they are attached to the feedthrough wires with inline barrel connectors constructed with BeCu and SS316 screws provided by KJLC. This two hemisphere design was chosen for a number of reasons, the first being any grid I could think of is too large to fit into the small hole of the chamber thus calling for a design that can be compressed then decompressed once inside the chamber, the second being with these two separately insulated grids it allows the ability to attach two AC leads as well as connecting a single DC lead, and the third would be the ease of precision construction in a small time frame. This grid can be replaced within a matter of minutes with a minimal amount of construction. The two ends of the conical filament fits perfectly into the ports of the 6-way cube. I am possibly switching to a more substantial feedthrough due to the fact that there is slight arcing at lower pressures. In spite of this, the design will remain the same except for the external dimensions of the feedthrough.
7.) This shows the grid installed along with the D2 gas feedthrough. This D2 gas feedthrough is all 1/4" swage-lok port connectors and elbows constructed out of SS. As shown, the grid tolerances are small but the fit is immaculate within the chamber allowing a relatively good amount of space to spare.
8.) This is the chamber with: the MD5 valve, power feedthrough, close coupling, D2 inlet, and a blank flange on the opposite side of the chamber behind the grid.
9.) This is the final product with the Lead glass viewport installed along with the second blank flange and 2.75"-1.33" conical reducer in the bottom of the image. This reducer (SS) is used to attach to the Turbo and roughing pump system.
10.) This is the first AC plasma out of the machine. This was created with an NST 15kv@30ma at around 80mbar.
Thank you for your patience.