K.M. Thompson

Development of a short-period superconducting undulator at APS

A planar superconducting undulator (SCU) with a period of 15 mm is under development at the Advanced Photon Source (APS). The intended users require a photon energy that can be tuned from 19 to 28 keV for inelastic X-ray scattering studies. The SCU design consists of two low-carbon-steel cores that are positioned above and below the beam chamber. There are 20 turns of NbTi/Cu superconducting (SC) wire within a coil cross section of 4.3 /spl times/ 4.0 (w /spl times/ h) mm/sup 2/. At a pole gap of 8 mm, the necessary average current density in the coil will be about 1 kA/mm/sup 2/ to achieve a peak field of 0.8 T on the beam axis. The design and fabrication progress of a 12-period prototype SCU are presented, and some challenging requirements are discussed.

Design and Development of Cryostable Superconducting Ohmic Heating Coils for a Tokamak

A conceptual design on the superconducting ohmic heating (OH) coil has been made for the GA/ANL TNS tokamak reactor studies. The primary advantage of a superconducting OH coil is the minimization of equipment and operational costs. This is primarily a result of the much reduced power supply and energy storage costs. Three-hundred megawatt peak power and 11-MW rms power would be required to drive a room-temperature copper OH coil system, as opposed to 16 and 4 MW, respectively, for a superconducting OH coil. Another reason is that, to reduce the overall TNS tokamak cost, the flux core of OH coils should be small. However, a much better utilization of the flux core can be achieved with superconducting OH coils by placing the support cylinder of superconducting toroidal field (TF) coils within the inner diameter of the superconducting OH coils, thus allowing the outer diameter of the OH coils to be in close contact with TF coils. Recent scoping studies indicate that superconducting OH coils will cost only half as much as room-temperature copper OH coils [1].

Design and tests of the injector synchrotron magnets for the 7-GeV Advanced Photon Source

Design and magnetic measurements of the pre-production dipole, quadrupole and sextupole magnets for the 7-GeV Advanced Photon Source (APS) injector synchrotron (IS) are described.<<ETX>>

Fabrication and tests of prototype quadrupole magnets for the storage ring of the Advanced Photon Source

Prototype quadrupole magnets for the Advanced Photon Source storage ring have been fabricated and tested. Mechanical stability of the magnet poles and acceptable field quality have been achieved. The measured magnetic fields in terms of multipole coefficients for the prototypes meet the requirements for the positron beam dynamics. Use of removable pole-tip geometries of pole-end bevels has been investigated in order to design the magnet endplate. In order to improve the excitation efficiency for the operation above 7 GeV, the pole geometry has been modified for the production magnets.<<ETX>>

Performance of quadrupole and sextupole magnets for the Advanced Photon Source storage ring

From the magnetic measurement data of several production quadrupole and sextupole magnets for the storage ring of the Advanced Photon Source, the excitation efficiencies and systematic and random multipole coefficients of the magnets are summarized. The designs of the magnets, which are constrained due to the geometry of the vacuum chamber, have rotation symmetries of 180/spl deg/ and 120/spl deg/. The production data meet the allowed tolerances of a few parts in 10/sup -4/ for the storage ring. >

Quadrupole magnet for the APS storage ring

An asymmetric core geometry has been selected for the quadrupole magnets in the storage ring of the Advanced Photon Source (APS) in order to accommodate the vacuum chamber and photon beam pipes. The requirements of the positron beam make it necessary that the magnet be able to produce a field gradient of 20-T/m with high accuracy. The design for this magnet has been fully developed in preparation for the construction of a prototype. Some unique features included in the design are described. Design choices are being validated by extensive magnetic-field calculations in both two and three dimensions. The results of these calculations are presented.<<ETX>>

A 10‐GeV, 5‐MW proton source for a muon‐muon collider

The performance parameters of a proton source which produces the required flux of muons for a 2‐TeV on 2‐TeV muon collider are: a beam energy of 10 GeV, a repetition rate of 30 Hz, two bunches per pulse with 5×1013 protons per bunch, and an rms bunch length of 3 nsec (1). Aside from the bunch length requirement, these parameters are identical to those of a 5‐MW proton source for a spallation neutron source based on a 10‐GeV rapid cycling synchrotron (RCS) (2). The 10‐GeV synchrotron uses a 2‐GeV accelerator system as its injector, and the 2‐GeV RCS is an extension of a feasibility study for a 1‐MW spallation source described elsewhere (3–9). A study for the 5‐MW spallation source was performed for ANL site‐specific geometrical requirements. Details are presented for a site‐independent proton source suitable for the muon collider utilizing the results of the 5‐MW spallation source study.

Feasibility study of a 1-MW pulsed spallation source

A feasibility study of a 1-MW pulsed spallation source based on a rapidly cycling proton synchrotron (RCS) has been completed. The facility consists of a 400-MeV H/sup -/ linac, a 30-Hz RCS that accelerates the 400-MeV beam to 2 GeV, and two neutron-generating target stations. The design time-averaged current of the accelerator system is 0.5 mA, and is equivalent to 1.04/spl times/10/sup 14/ protons per pulse. The linac system consists of an H/sup -/ ion source, a 2-MeV RFQ, a 70-MeV DTL and a 330-MeV CCL. Transverse phase space painting to achieve a Kapchinskij-Vladimirskij (K-V) distribution of the injected particles is accomplished by the charge exchange injection and programming of the closed orbit during the injection. The synchrotron lattice uses FODO cells of 90/spl deg/ phase advance. Dispersion-free straight sections are obtained by using a missing magnet scheme. Synchrotron magnets are powered by a dual-frequency resonance circuit that excites the magnets at a 20-Hz rate and de-excites them at a 60-Hz rate, resulting an effective rate of 30 Hz, and reducing the required rf power by 1/3. Details of the study are presented.

Design and measurement of the sextupole magnet for the APS storage ring

A prototype sextupole magnet has been designed, constructed, and measured for the storage ring of the Advanced Photon Source. The design approaches very closely to 120/spl deg/ rotation symmetry, in order to minimize all forbidden multipole components. The core is made of three identical stacks of laminations, each lamination consisting of two poles and the return yoke joining them. The antechamber of the thick aluminum vacuum chamber fits between two neighboring stacks. Computations and measurements of the sextupole strength B and multipole field components, both in the central region and integrated in the beam direction, show that the magnet meets the requirements for positron beam dynamics.<<ETX>>

Conceptual design for one megawatt spallation neutron source at Argonne

A feasibility study of a spallation neutron source based on a rapid cycling synchrotron which delivers a proton beam of 2 GeV in energy and 0.5 mA time-averaged current at a 30-Hz repetition rate is presented. The lattice consists of 90-degree phase advance FODO cells with dispersion-free straight sections, and has a three-fold symmetry. The ring magnet system will be energized by 20-Hz and 60-Hz resonant circuits to decrease the dB/dt during the acceleration cycle. This lowers the peak acceleration voltage requirement to 130 kV. The single turn extraction system will be used to extract the beam alternatively to two target stations. The first station will operate at 10 Hz for research using long wavelength neutrons, and the second station will use the remaining pulses, collectively, providing 36 neutron beams. The 400-MeV negative-hydrogen-ion injector linac consists of an ion source, rf quadrupole, matching section, 100-MeV drift-tube linac, and a 300-MeV coupled-cavity linac.<<ETX>>