[en] Linear accelerators based on superconducting magnet technology use a large number of relatively weak superconducting quadrupoles. In this case an iron dominated quadrupole is the most cost effective solution. The field quality in this magnet is defined by iron poles; the magnet air gap is minimal as are coil ampere-turns. Nevertheless, it has long racetrack type coils, which must be rigid and fixed by a mechanical structure to provide the needed mechanical stability. The novel concept of using circular superconducting coils in such a quadrupole type is described, with a discussion of quadrupole parameters, and results of 3D magnetic designs. Variants of short and long sectional quadrupoles and multipoles are presented.

[en] Superconducting Linear Accelerators include a superconducting magnet system for particle beam transportation that provides the beam focusing and steering. This system consists of a large number of quadrupole magnets and dipole correctors mounted inside or between cryomodules with SCRF cavities. Each magnet has current leads and powered from its own power supply. The paper proposes a novel approach to magnet powering based on using superconducting persistent current switches. A group of magnets is powered from the same power supply through the common, for the group of cryomodules, electrical bus and pair of current leads. Superconducting switches direct the current to the chosen magnet and close the circuit providing the magnet operation in a persistent current mode. Two persistent current switches were fabricated and tested. In the paper also presented the results of magnetic field simulations, decay time constants analysis, and a way of improving quadrupole magnetic center stability. Such approach substantially reduces the magnet system cost and increases the reliability.

[en] A novel concept of superconducting multipole corrector magnet is discussed. This magnet assembled from 12 identical racetrack type coils and can generate any combination of dipole, quadrupole and sextupole magnetic fields. The coil groups are powered from separate power supplies. In the case of normal dipole, quadrupole and sextupole fields the total field is symmetrical relatively the magnet median plane and there are only five powered separately coil groups. This type multipole corrector magnet was proposed for BTeV, Fermilab project and has following advantages: universal configuration, simple manufacturing and high mechanical stability. The results of magnetic design including the field quality and magnetic forces in comparison with known shell type superconducting correctors are presented

[en] Next Linear Collider (NLC) and Very Large Hadron Collider (VLHC) projects suppose to use permanent magnets as bending, focusing and correcting elements. Prototypes of two permanent magnet quadrupoles with variable strength were built and successfully tested in Fermilab. Quadrupoles have 12.7 mm aperture diameter, 100 T/m gradient with an adjustment range of 0 to -20%. Special designs provide high precision magnetic center stability during strength change. SmCo5 permanent magnet bricks were used in these prototypes. Rotational quadrupole consists of four sections. Two central sections are rotated in counter directions to adjust the strength. Magnetic shunt quadrupole design provides variable shunting of the magnetic flux. The numerical simulation, designs, measuring results are described

[en] The magnet system of the Very Large Hadron Collider (VLHC) Stage I is based on a superconducting 2 Tesla magnetic field combined function magnets. These magnets will have a room temperature iron core with two 20 mm air gaps. Magnetic field in both horizontally separated air gaps is excited by a single turn 100 kA superconducting transmission line. The alternative design with cold iron core, horizontally or vertically separated air gaps is under investigation. The cold iron option with horizontally separated air gaps reduces the amount of iron, which is one of the main cost driver for 233 km length magnet system of the future accelerator. The vertical beam separation decreases volume superconductor, heat load from synchrotron radiation and eliminates fringing field from a return bus. But the horizontal beam separation has lowest volume of iron core and as a result lower heat load for cryosystem during cooling down. All these options are discussed and comparison is made. Superconducting correction system, combined with the magnet, allowing to increase the maximum field is also under discussion. Preliminary cost analysis are made for all options

[en] An end-to-end performance calculation and comparison with beam tests was performed for the bunch-by-bunch digital transverse damper in the Fermilab Main Injector. Time dependent magnetic wakefields responsible for ''Resistive Wall'' transverse instabilities in the Main Injector were calculated with OPERA-2D using the actual beam pipe and dipole magnet lamination geometry. The leading order dipole component was parameterized and used as input to a bunch-by-bunch simulation which included the filling pattern and injection errors experienced in high-intensity operation of the Main Injector. The instability growth times, and the spreading of the disturbance due to newly misinjected batches was compared between simulations and beam data collected by the damper system. Further simulation models the effects of the damper system on the beam

[en] In order to produce muon beam of high enough quality to be used for a Muon Collider, its large phase space must be cooled several orders of magnitude. This task can be accomplished by ionization cooling. Ionization cooling consists of passing a high-emittance muon beam alternately through regions of low Z material, such as liquid hydrogen, and very high accelerating RF cavities within a multi-Tesla solenoidal focusing channel. But first high power tests of RF cavity with beryllium windows in solenoidal magnetic field showed a dramatic drop in accelerating gradient due to RF breakdowns. It has been concluded that external magnetic fields parallel to RF electric field significantly modifies the performance of RF cavities. However, magnetic field in Helical Cooling Channel has a strong dipole component in addition to solenoidal one. The dipole component essentially changes electron motion in a cavity compare to pure solenoidal case, making dark current less focused at field emission sites. The simulation of dark current dynamic in HCC performed with CST Studio Suit is presented in this paper.

[en] Helical Solenoids (HS) were proposed for a muon beam ionization cooling. There are substantial energy losses, up to 30 MeV/m, during the passing of the muon beam through the absorber. The main issue of such a system is the muon beam energy recovery. A conventional RF cavity is too large to be placed inside HS. In the paper the results of a dielectric-filled RF cavity design is presented. The proposed RF cavity has a helical configuration. Helical Cooling Channel (HCC) module design which includes high pressure vessel, RF cavity, and superconducting HS is presented. The parameters of these module sub-systems are discussed, and the results of muon beam tracking in combined magnetic and electric 3D fields are shown.

[en] The Advanced Hydrotest Facility (ANF), under study by LANL, utilizes large-bore superconducting quadrupole magnets to image protons for radiography of fast events. In this concept, 50-GeV proton bunches pass through a thick object and are imaged by a lens system that analyzes the scattered beam to determine object details. Twelve simultaneous views of the object are obtained using multiple beam lines. The lens system uses two types of quadrupoles: a large bore (48-cm beam aperture) for wide field of view imaging and a smaller bore (23 cm aperture) for higher resolution images. The gradients of the magnets are 10.14 T/m and 18.58 T/m with magnetic lengths of 4.3 m and 3.0 m, respectively. The magnets are sufficiently novel to present a design challenge. Evaluation and comparisons were made for various types of magnet design: shell and racetrack coils, cold and warm iron, as well as an active superconducting screen. Nb₃Sn cable was also considered as an alternative to avoid quenching under high beam-scattering conditions. The superconducting shield concept eliminates the iron core and greatly lessens the cryogenic energy needed for cool down. Several options are discussed and comparisons are made.

[en] The design and manufacturing of the first model of an International Linear Collider (ILC) Main Linac superconducting quadrupole is in progress at Fermilab. The quadrupole has a 78 mm aperture, a 36 T integrated gradient, and a cold mass length of 700 mm. A superferric magnet configuration with iron poles and four racetrack coils was chosen based on magnet performance, cost, and reliability considerations. Each coil is wound using enamel insulated, 0.5 mm diameter, NbTi superconductor. The quadrupole package also includes shell type dipole steering coils. The results of the quadrupole design, including magnetic and mechanical analyses, are presented. Specific issues related to the quadrupole magnetic center stability, superconductor magnetization and mechanical stability are discussed and analyzed. The magnet quench protection system, current leads, and mounting the quadrupole inside ILC Main Linac cryomodule will also be briefly discussed