Cryogen free conduction cooled NbTi superconducting magnet for a X-band klystron

Abstract

A cryogen free conduction cooled NbTi superconducting magnet for a X-band klystron was designed,fabricated, and tested successfully. The magnet has a room temperature bore of 190 mm. The rated field distribution, the NbTi coil is separated to three parts and a return yoke is set. The coil is cooled by a twostage Gifford-McMahon cycle refrigerator. The refrigeration capacity is 1.1 W at 6 K and 30 W at 40 K for each stage. Current leads are made of 2223 Bi-based oxide superconductor. The coil was cooled down to superconducting state from temperature in 85 hours. The ultimate temperature of the coil was below power. The magnet was tested successfully and no problem at all is 0.7 T. In order to meet the requested magnetic field fl . MAGNET DESIGN A. NbTi superconducting coilThe solenoid consists of three coils which are wound in series on a stainless steel bobbin. The cold head of the refrigerator is thermally connect-4K, and the coil was energized without quench to 18.5 A ed to each coil bv a coolling: busbar. The magnet " " has a iron yoke to fit the magnetic field distribuwhich was 105% of rated current. The power consumption of 6 kW is 118 of the normal conducting magnet. The thermal leak of 0.2 W into the coil was measured, tion required for the klystron. Figure 1 shows a which was the same value of the design.

Development of Prototype MGB 2 Superconducting Solenoid Magnet for High-Efficiency Klystron Applications

“…The klystrons need electron-beam-focusing solenoid magnets, and the energy consumption of a current Cu magnet is 20 kW for cooling the Joule heat of the magnet [2]. In the case of NbTi superconducting magnets for klystrons, the energy consumption was 6 kW in previous studies [3]. The MgB2 superconducting solenoid magnet is planned to reduce this energy consumption, 20 kW, to about one tenth.…”

Performance of MgB2 Superconductor Developed for High-Efficiency Klystron Applications

“…The power efficiency of the magnet is important because in an design option of the Compact Linear Collider 380 GeV (CLIC-380 GeV), the number of klystron magnets reaches 4,000-5,000 [8]. The power consumption of a typical copper magnet for klystron applications is 20 kW for cooling the Joule heat of the magnet [9], and in the case of a Nb-Ti superconducting magnet without liquid helium, the AC plug power is 6 kW, as shown in a previous study [10]. To achieve high efficiency magnets for klystrons (klystron magnets), we developed an MgB 2 wire and a magnet that can be operated at high temperatures and have low power consumption.…”

Applying Superconducting Magnet Technology for High-Efficiency Klystrons in Particle Accelerator RF Systems

“…The MgB2 superconducting magnet for Klystron electron beam focusing has been successfully demonstrated with the general performance of 0.8 T at 57.1 A, at Tcs = 29K, at an AC plug-power consumption of < 3 kW, realizing to save the AC plug power down to one seventh (nearly one order of magnitude). Comparisons of Cu, NbTi, MgB2, and HTS (GdB-CO/EuBCO) are summarized in Table II from a viewpoint of AC-plug power saving [8][9][10]. The simplified operation with no requirement for an active quench protection system is also an important feature and advantage.…”