Archive for February, 2008

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Uranium Chemistry

February 20, 2008

Uranyl peroxide Uranium and its pure compounds are just not readily available to the amateur scientist, element collector, or student in 2008. So what is one to do? Make these materials oneself, of course. (At left is a quantity of home-baked yellowcake.)

This is the inaugural post in what will become a short series, detailing how uranium and various pure compounds can be refined from the brute earth to serve personal needs. There are differences between what is done in industrial mining / milling operations and what can be realistically accomplished in a typical American domicile. There are also differences in the raw materials that could be obtained back in the good old days when our favorite applied inorganic chemistry texts were written (“Borrow a gallon of fuming nitric acid and some glycerin from your science-teacher…”), versus what can be obtained in the paranoid, restrictive world of today. Thus, my approach to uranium chemistry emphasizes practical techniques and materials that are available to today’s home-dweller. The foregoing discussion assumes a decent background in chemistry and mature attention to safety.

Uranium chemicals

Uranium compounds that can be easily prepared at home are shown in this photo. In vials, left to right: uranyl oxide (UO3); uranyl peroxide (UO4·nH2O); triuranium octoxide, U3O8; sodium diuranate (Na2U2O7·6H2O); uranium tetrafluoride (UF4·2.5H2O); “sodium peruranate” in solution; uranyl chloride (UO2Cl2) in solution. In front is an electroplated layer of uranium dioxide (UO2). Click “more” below for content (I will upload it as time permits).

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Farnsworth Fusor (“Carl’s Jr.”)

February 17, 2008

This post will serve as a documentation hub for my Farnsworth fusor hobby projects. I have used these devices as neutron generators for doing activation experiments at home and at college. The fusor is a simple spherical ion source / accelerator / collider that can be built on a shoestring budget with a minimum of technical background, enabling hobbyists to access some nuclear fusion reactions. This blog post isn’t intended to provide an adequate overview of the fusor’s physics or serve as a base for technical discussion–there are already some good websites out there with those purposes. Readers with questions or interest in this technology are encouraged to engage in the discussions on the Fusor Forum.

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“Carl’s Jr.” is my current fusor project, first operated in 2006.

Star dischargeCarl’s JrCathodeFusor systemModeratorCockroft-Walton

Specifications of “Carl’s Jr.” are provided below, with links to more detail and commercial suppliers for some components.

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While a student at Guilford College, I built the predecessor to Carl’s Jr., a larger but less innovative fusor with which I did some novel neutron activation experiments.

OldFusorPoissor OldFusorTopViewxray machine sparking

Specifications of my Guilford fusor are provided below.

  • Typical operating conditions: 67 kVp, 15 mA, 10 mtorr, ~3E+06 neutrons / sec.
  • Vacuum chamber: 2 x 8″ 304SS hemispheres, 10″ equatorial CF flanges
  • Chamber ports: 2 x QF25, 1 x 2.75″ CF, 1 x special feedthrough solder lip
  • Cathode: 6 x 2.5″ loops of 0.025″ dia. 316SS wire, construction by spot welding
  • Ion source: none
  • HV feedthrough: surplus 100 kV vacuum-rated feedthrough, air-insulated
  • Gas system: 5o-liter LB cylinder of deuterium, 2 series needle valves
  • High voltage system: 135 kVp x-ray supply, controlled by Variac and magnetic amplifier
  • Vacuum system: Varian 50 LPS baby turbopump system
  • Cooling system: forced-convection air cooling (ShopVac)
  • Neutron irradiator: Water in VHS cases; paraffin canning wax

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Fusor Experiments

Documents

  • My undergraduate thesis for the physics department of Guilford College, entitled “Neutron Activation Using a Farnsworth Fusor” (2003) can be downloaded here. An accompanying PowerPoint presentation can be downloaded here.

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