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#2 FAQ - Current needed in a fusor.

Posted: Tue Feb 25, 2014 6:46 pm
by Richard Hull
Fusion occurs at all current levels. The current needed to do fusion to advantage is a function of the number one and most important factor VOLTAGE!

As noted in the companion voltage FAQ, the probability of doing fusion, at all, increases with increasing applied voltage to the fusor. The current merely determines the number of current elements (fuel ions) present at any one time to be able to do fusion. More current means more ions and thus, more opportunity for fusion at any given voltage due to an increase of usable, accelerated, fusion-ready fuel elements.

These deuterons accelerate and many or most will slam into the inner grid, heating it. We must be mindful of overheating and possible melting the grid. This is a function of energy delivered to the fusor based on the power relationship of voltage times running current. Once we reach a good voltage to do fusion, we must be mindful of the current and not let it get so high that grid heating will increase with increased current and destroy it. (melting) We do not want to fuse the grid structure.....We want to fuse deuterium atoms.


In general, the bulk of fusion in amateur systems demands a minimum of to 10 milliamps of current when running at fusion voltages. More current capability in the power supply is highly desireable and offers a cushion against overdriving the power supply. 15-20ma is ideal. More is better.


Part of the operational running of a fusor to advantage is a delicate and proper balance of voltage, current and pressure...... Pressure?!

That is correct! Pressure can limit your applied voltage and current or support it. It is one of the critical variables and intimately interacts with the electrical energy to limit or promote the fusion mission goal. Pressure is the one reason no hard and fast voltage or current can be rigidly specified to do fusion.

A companion FAQ is generated to explain Pressure and can be found in the vacuum forum at:


Richard Hull