Editing Inertial electrostatic confinement (section)

===1960s===

[[File:US3386883 - fusor.png|thumb|upright=0.8|{{US patent|3,386,883}} - Schematic from Philo Farnsworth 1968 patent. This device has an inner cage to make the field, and four ion guns on the outside.]]

In his work with vacuum tubes, [[Philo Farnsworth]] observed that electric charge would accumulate in regions of the tube. Today, this effect is known as the [[multipactor effect]].<ref>Cartlidge, Edwin. The Secret World of Amateur Fusion. Physics World, March 2007: IOP Publishing Ltd, pp. 10-11. {{ISSN|0953-8585}}.</ref> Farnsworth reasoned that if ions were concentrated high enough they could collide, and fuse. In 1962, he filed a patent on a design using a positive inner cage to concentrate plasma, in order to achieve nuclear fusion.<ref>US Patent 3,258,402 June 28, 1966</ref> During this time, [[Robert L. Hirsch]] joined the [[Philo Farnsworth|Farnsworth Television labs]] and began work on what became the [[fusor]]. Hirsch patented the design in 1966<ref>US Patent 3,386,883 June 4, 1968</ref> and published the design in 1967.<ref name="Hirsch">{{cite journal |last1=Hirsch |first1=Robert L. |title=Inertial-Electrostatic Confinement of Ionized Fusion Gases |journal=Journal of Applied Physics |volume=38 |issue=7 |pages=4522–4534 |year=1967 |bibcode=1967JAP....38.4522H |doi=10.1063/1.1709162}}</ref> The [[Robert L. Hirsch|Hirsch]] machine was a 17.8&nbsp;cm diameter machine with 150 kV voltage drop across it and used ion beams to help inject material.

Simultaneously, a key plasma physics text was published by [[Lyman Spitzer]] at [[Princeton University|Princeton]] in 1963.<ref>Lyman J Spitzer, "The Physics of Fully Ionized Gases" 1963</ref> Spitzer took the ideal gas laws and adapted them to an ionized plasma, developing many of the fundamental equations used to model a plasma. Meanwhile, [[magnetic mirror]] theory and [[direct energy conversion]] were developed by [[Richard F. Post]]'s group at [[LLNL]].<ref>{{cite journal |last=Kelley |first=G G |title=Elimination of ambipolar potential-enhanced loss in a magnetic trap |journal=Plasma Physics |publisher=IOP Publishing |volume=9 |issue=4 |date=1967-01-01 |pages=503–505 |issn=0032-1028 |doi=10.1088/0032-1028/9/4/412}}</ref><ref name="Mirror Systems 1969">"Mirror Systems: Fuel Cycles, loss reduction and energy recovery" by Richard F. Post, BNES Nuclear fusion reactor conferences at Culham laboratory, September 1969.</ref> A magnetic mirror or magnetic bottle is similar to a biconic cusp except that the poles are reversed.