The construction of HT-7 Superconducting Tokamak , undertaken by ASIPP was completed in Hefei , P.R.China in December 1994. Consequently, this apparatus successfully passed the cooling down & engineering test. The first plasma current was got on December 28 , 1994. The description of this apparatus & its general assembly has already appeared in previous SOFE. Since there are some problems during nearly two years of series operating , especially LHe leak in the cryostat at low temperature. On the basis of experience gathered during the operating of HT-7 equipment, the proposal of rebuilding of HT-7 current lead unit was put forward.

The LHe system including the current leads is one of most important components of HT-7 Superconducting Tokamak equipment. Its performance directly affects the operating qualification of this apparatus.

The main purposes of rebuilding of the current lead unit has been determined in order to :(1) lower mass flow of the gas-cooled lead ; (2) increase pressure measure of inlet and outlet lines; (3) improve temperature measure for raising measure accuracy; (4) chiefly solve the LHe leak problem of HT-7 cryostat at low temperature for lowering the heat load of HT-7 equipment.

The reconstruction of the current lead unit ended in January 1996. All the design specifications were fully achieved & exceeded: The mass flow of gas-cooled leads was 0.7g/s (5000A), which was one-third consumption of the former leads. Leak rate of LHe system including the current leads was less than 8x10^-8 Pa.m³ /s (vacuum pressure was 8x10^-1Pa for cryostat).

The paper presents technical schemes & technological methods on the reconstruction of HT-7 current lead unit to satisfy above requirements. At first , structure characteristics & design parameters on the current leads are described. The comparison between the former leads and the new ones is made. Secondly, fabricating steps necessary to reconstruct the leads & a series of technological methods to solve the techniques are reported. Then, based on the stress analysis & mechanical properties at low temperature on some kinds of materials used in LHe system, the stress weak links & improvement methods are discussed. Finally, the vacuum test and status of LHe system including the current leads after rebuilding are given.