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A quite large negative voltage of about -30,000 Volts needs to be applied to the tungsten grid inside the reactor chamber to achieve fusion. Hence there is a large difference of electric potentials which in air can arc for multiple centimeters or more if humid. Such an arc effectively acts like a short circuit and would not only cut power to the fusion process, but also endangers people and causes damage all kinds of components: whatever is along or at an end of it can reach thousands of degrees (also known as arc welding), while the increased current can damage the transformer or other electric parts.
The aim of this component is to guarantee a steady controlled inflow of deuterium gas into the reactor chamber. Only a very small amount is needed at a few µbar, which on one hand makes it easy to produce deuterium at a sufficient rate, but on the other hand requires special components to regulate a small flow. Why deuterium? The element most commonly associated with fusion is hydrogen. It is, after all, what the solar core expends to create helium and lots of power.
After multiple considerations I decided to make a proper control system which tracks all measurements. A self-made control panel with dedicated buttons and displays allows the operator, me, to quickly observe and adjust critical values. But at the same time the system can react to changes quicker than a human, the latter thus only acting as a backup. As an additional feature it in principle allows remote control, in which case however one must add additional safeties including an independent fail-safe shut-off in addition to the local emergency shut-down button.
As elaborated in the page on deuterium a home fusion reactor almost exclusively relies on this gas as fuel. Sadly it is not easy and cheap to acquire. Luckily a fusor only uses minute amounts. Problematicly most of it gets wasted. Deuterium can be bought in expensive metal cylinders. It is cheaper to extract it from heavy water (D2O), water with deuterium instead of the usual protium. Industrially it is produced electrochemically via various processes which utilize the small but notable chamical differences between protium and deuterium.
Most functional fusor chambers seem to be around 10 to 20 centimeters in diameter while sophisticated setups can work above and below. They should be made of stainless steel or similar material to withstand heat and vacuum, while also blocking x-rays generated during operation. In particular, aluminium (more permeable to x-rays) and glass (again x-rays; can spontaneously break due to stresses, especially with uneven heating from electron beams; UV) are bad choices.
Originally this was intended as the only controller and would mount the control panel directly on top. The other systems would be entirely independent and manual, especially the high voltage control. When development and setup progressed it became clear that a more complex system serves my intended purposes better. The decision to change for the current design happened before the connectors and container were finalized, therefor this later change did not cause much issue.
The desire to look at the tiny star-like center entertaining life fusion is undeniable. Where else can one safely watch an ongoing nuclear reaction right before one’s nose; the famous “star in a bottle”? Hence an observation window is effectively a must to quench this urge. A further justification is found in the ability to observe the grid while hot and charged, where disparities in shape, field and flow become visible.
Current Projects This is an overview of some of my larger projects I am working on, completed or plan to do at some point. It goes from simple woodworking to reactor engineering. Wooden fume hood to safely do chemical experiments and purifications, ater extended to double as a sand blasting chamber. (finished/in use) Basic 3D printing for arising needs; my current printer is an Anycubic Mega SE. (finished/ongoing) Various microcomputer builds (Arduino, Raspberry Pi) in support of multiple projects.
What’s a “fusor”? One of the coolest physics devices within reach of an amateur at home is the Farnsworth-Hirsch fusor, a “star in a bottle”. It aims to invoke ungodly forces onto the building blocks of matter to smash them together so hard, they create different elements and useful particles: the modern realization of the alchemists’ dream of transmutation. Unlike larger fusion reactors such as a doughnut-shaped massive tokamak or a sleekly twisted stellerator, they are usually spherical, quite small, don’t cost billions of dollars, and do not aim to solve the energy crisis.
Hallo Jana & Lukas. This is a test