在Tokamak装置中用中空超导环段冻结环向磁场的设想

本文提出一个设想:即将n个中空超导圆柱体放置于n饼纵场线圈之中,分段冻结环向磁场,则其所需要的电功率将比常规线圈降低到2/n倍。我们知道超导材料的冻结场可近似地写为。H_fj(r,T)=H_fj(r,0)[1-(T/(T_c))²。因此选定T=T₁,当轴向场H在大圆环的内壁达到H≥H_fj(r,T₁)时,中空体的内边缘达到临界场,则场进入中空区,再使H降到零,中

A PROPOSAL OF FREEZING TOROIDAL MAGNETIC FIELD WITH THE SECTIONS OF SUPERCONDUCTING HOLLOWED CYLLINDER IN TOKAMAK APPARATUS

In the paper, we suggest a proposal that if n sections of the superconducting hollowed cyllinder which has been longitudinally cut are put into n longitudinal field coils for Tokamak apparatus, electric power of longitudinal field coils can be reduced to 2/n by sectional freezing of toroidal field,It is well known that freezing field H_fj of Superconducting material may be expressed approximately by the following equation: H_fj(r,T)=/H_fj(r, 0)[1-(T/T_c)²] Consequently, if we select that T = T₁, the critical field will be reached at the internal wall of the superconducting hollowed cyllinder and magnetic field will go into it when the magnetic field reaches H_in≥ H_fj(r,T₁). Then the magnetic field H will decrease to zero and the temperature will also decease to T₂ which is far below the temperature T₁. Thus this hollowed cyllinder can't be effected when magnetic field is being freezed in the neighbonring superconducting hollow cyllinder.Since electric power required is decreased by 2/n times, the power supply of middle sized apparetus operating at present is sufficient to provide power reactor.Since superconducting hollowed cyllinders with freezed magnetic field H_fj(r, T₁) are put at temperature T₂, after plasma is built it also can well equilibrate and stabilize plasma together with equilibrating field and feed backing field. Not only the role of Copper shells for equilibrating and stabizing plasma may be largely expanded by the combination of sections of the superconducting hollow cyllinder and copper shells with toroidal cuts in the internal wall, but also the thickness of copper shell can be decreased.Although electric power required for freezing toroidal field is greater than the power required by superconducting solenoidal magnet, however the local rise of temperature caused by the small mechanical movement of conductor due to the much large electromagnetic force in the superconducting magnet can be avoided.