1930s Mark Oliphant adapts
Cockcroft and
Walton's particle accelerator at the
Cavendish Laboratory to create
tritium and
helium-3 by nuclear fusion.
1950s Three researchers at
LANL including
Jim Tuck first explored the idea, theoretically, in a 1959 paper. The idea had been proposed by a colleague. The concept was to capture electrons inside a positive cage. The electrons would accelerate the ions to fusion conditions. Other concepts were being developed which would later merge into the IEC field. These include the publication of the
Lawson criterion by
John D. Lawson in 1957 in England. This puts on minimum criteria on power plant designs which do fusion using hot
Maxwellian plasma clouds. Also, work exploring how electrons behave inside the
biconic cusp, done by
Harold Grad group at the
Courant Institute in 1957. A biconic cusp is a device with two alike magnetic poles facing one another (i.e. north-north). Electrons and ions can be trapped between these.
1960s 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. 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. During this time,
Robert L. Hirsch joined the
Farnsworth Television labs and began work on what became the
fusor. Hirsch patented the design in 1966 and published the design in 1967. The
Hirsch machine was a 17.8 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 in 1963. 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. A magnetic mirror or magnetic bottle is similar to a biconic cusp except that the poles are reversed.
1980s In 1980
Robert W. Bussard developed a cross between a fusor and
magnetic mirror, the
polywell. The idea was to confine a non-neutral plasma using magnetic fields. This would, in turn, attract ions. This idea had been published previously, notably by
Oleg Lavrentiev in Russia. Bussard patented the design and received funding from
Defense Threat Reduction Agency,
DARPA and the US
Navy to develop the idea.
1990s Bussard and
Nicholas Krall published theory and experimental results in the early nineties. In response, Todd Rider at
MIT, under
Lawrence Lidsky developed general models of the device. Nevins argued that the particles would build up
angular momentum, causing the dense core to degrade. In the mid-nineties, Bussard publications prompted the development of fusors at the
University of Wisconsin–Madison and at the
University of Illinois at Urbana–Champaign. Madison's machine was first built in 1995.
George H. Miley's team at Illinois built a 25 cm fusor which has produced 107 neutrons using deuterium gas and discovered the "star mode" of fusor operation in 1994. The following year, the first "US-Japan Workshop on IEC Fusion" was conducted. This is now the premier conference for IEC researchers. At this time in Europe, an IEC device was developed as a commercial neutron source by
Daimler-Chrysler Aerospace under the name FusionStar. In the late 1990s, amateur fusion hobbyist Richard Hull began building fusors in his home. In March 1999, he achieved a neutron rate of 105 neutrons per second. Hull and Paul Schatzkin started fusor.net in 1998. Through this open forum, since 1998, a community of amateur fusioneers have built homemade fusion reactors using fusors.
2000s Despite demonstration in 2000 of 7200 hours of operation without degradation at high input power as a sealed reaction chamber with automated control the FusionStar project was canceled and the company NSD Ltd was founded. The spherical FusionStar technology was then further developed as a linear geometry system with improved efficiency and higher neutron output by NSD Ltd. which became NSD-Fusion GmbH in 2005. In early 2000, Alex Klein developed a cross between a polywell and ion beams. In response to Riders' criticisms, researchers at
LANL reasoned that a plasma oscillating could be at local thermodynamic equilibrium; this prompted the POPS and Penning trap machines. At this time,
MIT researchers became interested in fusors for space propulsion and powering space vehicles. Specifically, researchers developed
fusors with multiple inner cages. In 2005, Greg Piefer founded
Phoenix Nuclear Labs to develop the fusor into a neutron source for the mass production of medical isotopes.
Robert Bussard began speaking openly about the Polywell in 2006. He attempted to generate interest in the research, before dying from multiple myeloma in 2007. His company was able to raise over ten million in funding from the US Navy in 2008 and 2009.
2010s Bussard's publications prompted the
University of Sydney to start research into electron trapping in polywells in 2010. The group has explored theory, modeled devices, built devices, measured trapping and simulated trapping. These machines were all low power and cost and all had a small
beta ratio. In 2010, Carl Greninger founded the northwest nuclear consortium, an organization which teaches nuclear engineering principles to high school students, using a 60 kvolt fusor. In 2012, Mark Suppes received attention, for a fusor. Suppes also measured electron trapping inside a polywell. In 2013, the first IEC textbook was published by
George H. Miley. ==Designs with cage==