overloads. Extremely high pulse ratings of second and third-generation devices also make them useful for generating large power pulses in areas including particle and plasma physics, where they are starting to supersede older devices such as thyratrons and triggered spark gaps. High pulse ratings and low prices on the surplus market also make them attractive to the high-voltage hobbyists for controlling large amounts of power to drive devices such as solid-state Tesla coils and coilguns. Patent issues The device proposed by J. D. Plummer in 1978 (US Patent Re.33209) is the same structure as a thyristor with a MOS gate. Plummer discovered and proposed that the device can be used as a transistor although the device operates as a thyristor in higher current density level. The device proposed by J. D. Plummer is referred here as “Plummer’s device.” On the other hand, Hans W. Becke proposed, in 1980, another device in which the thyristor action is eliminated under any device operating conditions although the basic device structure is the same as that proposed by J. D. Plummer. The device developed by Hans W. Becke is referred here as “Becke’s device” and is described in US Patent 4364073. The difference between “Plummer’s device” and “Becke’s device” is that “Plummer’s device” has the mode of thyristor action in its operation range and “Becke’s device” never has the mode of thyristor action in its entire operation range. This is a critical point, because the thyristor action is the same as so-called “latch-up.” “Latch-up” is the main cause of fatal device failure. Thus, theoretically, “Plummer’s device” never realizes a rugged or strong power device which has a large safe operating area. The large safe operating area can be achieved only after “latch-up” is completely suppressed and eliminated in the entire device operation range. However, the Becke's patent (US Patent 4364073) did not disclose any measures to realize actual devices. Despite Becke's patent describing a similar structure to Baliga's earlier IGBT device, several IGBT manufacturers paid the license fee of Becke's patent. Toshiba commercialized “non-latch-up IGBT” in 1985. Stanford University insisted in 1991 that Toshiba's device infringed US Patent RE33209 of “Plummer’s device.” Toshiba answered that “non-latch-up IGBTs” never latched up in the entire device operation range and thus did not infringe US Patent RE33209 of “Plummer’s patent.” Stanford University never responded after Nov. 1992. Toshiba purchased the license of “Becke’s patent” but never paid