The electrostatic force caused by positively charged nuclei are very strong over long distances, but at short distances the nuclear force is stronger. As such, the main technical difficulty for fusion is getting the nuclei close enough to fusion. Distances not to scale.

Click this LINK to visit the original image and attribution information. Right click on the image to save the 800px teaching JPEG.



The electrostatic force caused by positively charged nuclei are very strong over long distances, but at short distances the nuclear force is stronger. As such, the main technical difficulty for fusion is getting the nuclei close enough to fusion. Distances not to scale.