Background: The Accelerator Driven Subcritical System (ADS) uses a proton beam incident on a target to produce neutrons used in a nuclear reactor to process spent fuel in two ways: to accelerate its decomposition into non-radioactive waste

and to increase the rate at which it is recycled into nuclear fuel. Two cryomodules

each consisting of 7 superconducting spoke cavities

7 superconducting magnets and 7 beam position monitors

are used to accelerate the proton beams from 3.2MeV to 10MeV. The superconducting magnet contains a solenoid for beam focusing and two correctors for orbit correction

it is a key component for ADS injection. Purpose: This study aims at a short superconducting magnet design to meet the required integral field strength and to reduce the leakage field at the nearby superconducting spoke cavities. The design current for the solenoid is 210 A. Methods: The main solenoid and two bucking solenoids plus the iron yoke were used to meet the leakage field requirements which is less than 1 G at a distance of 270 mm from the solenoid center. In order to shorten the magnet length to 170mm

special design methods were taken for the magnet cryostat by removing two conflicts flanges and replacing them with the direct Al ring seal methods. A kind of conducted the current leads similar as that of Large Hadron Collider (LHC) corrector magnets was applied to the 2.1-K

3 100-Pa cryogenic system. The small store energy magnet led to the introduction of active quench detected system

which is much more reliable. Two short magnets and two spoke cavities were installed inside a test cryomodule to test the online operation properties of the SC magnet and the SC spoke cavity. Results: A quench performance in the vertical test shows that the operating current of the solenoid magnet can reach above 300 A after natural quenching on three occasions during current ramping (260A

268A and 308A). Online operating test shows that two magnets can work at 4.2K and 2.1K

respectively. The quench protection system worked well when two quenches occurred as the liquid helium level decreased. Conclusion: The online operation for the two magnets confirms the physical and the mechanical design

the reliability of the quench detection technique. Abstract