Magnetization anomaly of Nb3Al strands and instability of Nb3Al Rutherford cables

Using a Cu stabilized Nb{sub 3}Al strand with Nb matrix, a 30 meter long Nb{sub 3}Al Rutherford cable was made by a collaboration of Fermilab and NIMS. Recently the strand and cable were tested. In both cases instability was observed at around 1.5 Tesla. The magnetization of this Nb{sub 3}Al strand was measured first using a balanced coil magnetometer at 4.2 K. Strands showed an anomalously large magnetization behavior around at 1.6 T, which is much higher than the usual B{sub c2} {approx} 0.5 Tesla (4.2 K) of Nb matrix. This result is compared with the magnetization data of short strand samples using a SQUID magnetometer, in which a flux-jump signal was observed at 0.5 Tesla, but not at higher field. As a possible explanation for this magnetization anomaly, the interfilament coupling through the thin Nb films in the strands is suggested. The instability problem observed in low field tests of the Nb{sub 3}Al Rutherford cables is attributed to this effect

Observation of the acceleration of a single bunch by using the induction device in the kek proton synchrotron

A single rf bunch in the KEK proton synchrotron was accelerated with an induction acceleration method from the injection energy of 500 MeV to 5 GeV.</p

Three dimensional FEM quench simulations of superconducting strands

The detailed phenomena in quench starting of Nb{sub 3}Sn strands are simulated in 3-D and in time using ANSYS and FEMLAB programs. The current sharing between the superconductor and copper stabilizer in strands at the beginning of a quench was studied and displayed in time. The differences in copper configuration and RRR value of copper were found to have large effect to the stability and quench propagation velocity. The MPZ theory was found to be effective for 3D multifilament situation

Design study of 45-mm bore dipole magnet for 11 to 12 tesla field

Two designs of 45mm bore dipole magnets are described about their magnetic characteristics. The first one has a 25mm thick collar with overall diameter of 520 mm. The other one has a 9-mm thin spacer with the overall diameter of 434 mm. Both of them have good field regions of 10{sup -4}, 28 mm wide horizontally and 24 mm wide vertically. With further adjustment of higher harmonics, the good field region can be horizontally increased to 33 mm. With the installation of a beam screen, the estimated vacuum space available for the beam operation is 33 mm wide horizontally and 22 mm wide vertically. If we assume that the total degradation of short sample data is 18.5%, the maximum central field values at quench current will be between 11.3 and 11.5 T

Racetrack-shape fixed field induction accelerator for giant cluster ions

A novel scheme for a racetrack-shape fixed field induction accelerator (RAFFIA) capable of accelerating extremely heavy cluster ions (giant cluster ions) is described. The key feature of this scheme is rapid induction acceleration by localized induction cells. Triggering the induction voltages provided by the signals from the circulating bunch allows repeated acceleration of extremely heavy cluster ions. The given RAFFIA example is capable of realizing the integrated acceleration voltage of 50 MV per acceleration cycle. Using 90° bending magnets with a reversed field strip and field gradient is crucial for assuring orbit stability in the RAFFIA

Experimental Demonstration of the Induction Synchrotron

We report an experimental demonstration of the induction synchrotron, the concept of which has been proposed as a future accelerator for the second generation of neutrino factory or hadron collider. The induction synchrotron supports a superbunch and a superbunch permits more charge to be accelerated while observing the constraints of the transverse space-charge limit. By using a newly developedinduction acceleration system instead of radio-wave acceleration devices, a single proton bunch injected from the 500 MeV booster ring and captured by the barrier bucket created by the induction step voltages was accelerated to 6 GeV in the KEK proton synchrotron