Editing Tokamak (section)

=== First tokamaks ===
By this time, Soviet researchers had decided to build a larger toroidal machine along the lines suggested by Sakharov. In particular, their design considered one important point found in Kruskal's and Shafranov's works; if the helical path of the particles made them circulate around the plasma's circumference more rapidly than they circulated the long axis of the torus, the kink instability would be strongly suppressed.<ref name=criterion/>

(To be clear, Electrical current in coils wrapping around the torus produces a toroidal magnetic field inside the torus; a pulsed magnetic field through the hole in the torus induces the axial current in the torus which has a poloidal magnetic field surrounding it; there may also be rings of current above and below the torus that create additional poloidal magnetic field. The combined magnetic fields form a helical magnetic structure inside the torus.)

Today this basic concept is known as the ''[[Safety factor (plasma physics)|safety factor]]''. The ratio of the number of times the particle orbits the major axis compared to the minor axis is denoted ''q'', and the ''Kruskal-Shafranov Limit'' stated that the kink will be suppressed as long as ''q'' > 1. This path is controlled by the relative strengths of the externally induced magnetic field compared to the field created by the internal current. To have ''q'' > 1, the external magnets must be much more powerful, or alternatively, the internal current has to be reduced.<ref name=criterion/>

Following this criterion, design began on a new reactor, T-1, which today is known as the first real tokamak.<ref name=tokomag/> T-1 used both stronger external magnetic fields and a reduced current compared to stabilized pinch machines like ZETA. The success of the T-1 resulted in its recognition as the first working tokamak.<ref name="autogenerated1">{{cite web |last1=Arnoux |first1=Robert |title=Which was the first 'tokamak' – or was it 'tokomag'? |url=https://www.iter.org/newsline/55/1194 |website=ITER |date=27 October 2008 |access-date=6 November 2018}}</ref>{{sfn|Shafranov|2001}}<ref>{{cite web| url = http://vant.iterru.ru/vant_2012_1/naj.pdf| title = К столетию со дня рождения Н. А. Явлинского}}</ref><ref>{{cite journal| url = http://ufn.ru/ufn01/ufn01_8/Russian/r018l.pdf| title = В. Д. Шафранов "К истории исследований по управляемому термоядерному синтезу"| journal = Успехи Физических Наук| date = August 2001| volume = 171| issue = 8| page = 877}}</ref>
For his work on "powerful impulse discharges in a gas, to obtain unusually high temperatures needed for thermonuclear processes", Yavlinskii was awarded the [[Lenin Prize]] and the [[State Stalin Prize|Stalin Prize]] in 1958. Yavlinskii was already preparing the design of an even larger model, later built as T-3. With the apparently successful ZETA announcement, Yavlinskii's concept was viewed very favourably.{{sfn|Shafranov|2001|p=841}}<ref>{{cite web |title=ОТЦЫ И ДЕДЫ ТЕРМОЯДЕРНОЙ ЭПОХИ |url=http://www.ras.ru/digest/showdnews.aspx?id=578d7525-c224-4f92-9a57-ed7113cb2c75&print=1 |access-date=6 November 2018}}</ref>

Details of ZETA became public in a series of articles in ''Nature'' later in January. To Shafranov's surprise, the system did use the "frozen in" field concept.{{sfn|Shafranov|2001|p=841}} He remained sceptical, but a team at the [[Ioffe Institute]] in [[St. Petersberg]] began plans to build a similar machine known as Alpha. Only a few months later, in May, the ZETA team issued a release stating they had not achieved fusion, and that they had been misled by erroneous measures of the plasma temperature.{{sfn|Herman|1990|p=53}}

T-1 began operation at the end of 1958.{{sfn|Smirnov|2009|p=2}}{{efn|Although one source says "late 1957".<ref name=tokomag/>}} It demonstrated very high energy losses through radiation. This was traced to impurities in the plasma due to the vacuum system causing outgassing from the container materials. In order to explore solutions to this problem, another small device was constructed, T-2. This used an internal liner of corrugated metal that was baked at {{convert|550|C}} to cook off trapped gasses.{{sfn|Smirnov|2009|p=2}}