11. A fusion plasma shaped like a twisted bow tie is confined inside a magnetic mirror . 12. This is an improvement over the simpler magnetic mirror . 13. Magnetic mirrors can reflect plasma when it moves from a low to high density field.14. By the late 1960s, magnetic mirror confinement was considered a viable technique for producing fusion energy. 15. This effect is known as the magnetic mirror . 16. So how do magnetic mirrors work, then? 17. In 1980 Robert W . Bussard developed a cross between a fusor and magnetic mirror , the polywell. 18. A major area of research in the early years of fusion energy research was the magnetic mirror . 19. It was first suggested by Richard F . Post in conjunction with magnetic mirrors , in the late sixties. 20. Though particles can be reflected to some extent with magnetic mirrors , even these allow many particles to pass.