A superconducting electron cooler with an adiabatic expansion factor of 100 was designed for high-precision experiments and high-speed cooling. The gun solenoid is a liquid-helium-free superconducting magnet with a 20-cm room-temperature bore, which can produce a magnetic field of up to 3.5 T. An electron beam is expanded from a diameter of 5 to 50 mm in a gradually decreasing solenoid field from 3.5 T to 35 mT. With this cooler, a transverse electron temperature on the order of 1 meV was attained. The longitudinal cooling force was measured with an induction accelerator as functions of the ion and electron currents, and the expansion factor. The longitudinal cooling force does not depend much on the expansion factor.

A liquid-helium-free superconducting electron cooler at the storage ring TARN II

A Stern–Gerlach atomic-beam ion source (ABS) with an electron cyclotron resonance (ECR) ionizer and a Cs gas target as charge exchange units will replace the Munich Lamb–Shift polarized hydrogen source. The goal is to achieve intense negative beams of polarized H− and D− of high brightness for injection into the 14 MV MP tandem accelerator and beam intensity of about 2 μA on the target. At the entrance of the ECR ionizer the observed intensity of the neutral beam of polarized atoms is 6.4±0.4×1016 H/s, equivalent to 10 particle/mA before ionization. Comparing beam transport calculations with beam intensity measurements under various conditions allows a consistent description of the beam formation in the ABS with respect to the degree of dissociation (≃80%), peaking (≃1.6), beam absorption (≃40%), and pumping speeds to be made.

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Beam formation at the Munich atomic beam source

The IUCF high intensity polarized ion source (HIPIOS) has been completed and installed in the 600 kV terminal. The design was originally based on the source in operation at TUNL, which employs cold (∼30 K) atomic beam technology and an electron cyclotron resonance ionizer. Development of the reliability and intensity of the atomic beam source will be described. An atomic beam flux of 5.0×1016 atoms/sec is estimated to be incident on the ECR ionizer. Preliminary testing of a multiple grid, high conductance, extraction system on the ECR ionizer has resulted in an extracted current of 500 μA attributable to the atomic beam, as measured 30 cm downstream of the ECR ionizer. After a mass analysis magnet, 245 μA are measured with a normalized emittance of 0.78 π‐mm‐mrad.

Polarized ion source development at IUCF

To increase the polarized proton beam intensity in the IUCF Cooler ring, this ring will be equipped with a new injector consisting of a 7 MeV linear accelerator and an 80 MeV Cooler Injection Synchrotron (CIS). The linear accelerator will accelerate negative hydrogen ions which will be strip-injected into CIS. Tracking calculations have been made to estimate the beam intensity that can be achieved within a specified emittance.

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Stripping injection into the new booster ring at IUCF

The IUCF high intensity polarized ion source has been completed and installed in the 600 kV terminal. The design is based on the source in operation at TUNL, which employs cold (/spl sim/30 K) atomic beam technology and an electron cyclotron resonance ionizer. It is expected to produce 100/spl mu/A DC H/spl I.oarrsup +/ and D/spl I.oarrsup +/ ion beams with a polarization of 75% or greater. Coupled with a wideband and resonant bunching system and a high transmission beam line into the injector cyclotron, the source should allow 10/sup 10/ protons to be stored in the electron cooled storage ring in a few seconds. Results from source development and project status will be described. >

The IUCF High Intensity Polarized Ion Source Project

The IUCF (Indiana University Cyclotron Facility) 270-keV electron cooling system has demonstrated collection efficiencies of 100% (+0/-2 p.p.m.) operating with a 2-A electron beam (0.4 A/cm/sup 2/). In addition, a very complete set of longitudinal drag rate measurements have been completed. These measurements span rest frame electron-proton velocity differences of over three orders of magnitude and include the region where the average longitudinal electron-proton velocity difference is less than the electron beam longitudinal velocity spread (a region which has not previously been measured). No obvious Schottky signal suppression (evidence of beam crystallization) has been observed for low-intensity cooled proton beams, though many interesting collective phenomena have been observed for high-intensity cooled proton beams. >

Status and performance of the IUCF 270 keV electron cooling system

In order to meet experimental requirements an ANAC source is being replaced with a modern high intensity source expected to yield in excess of 100 mu A DC H/sup +/ and D/sup +/ ion beams and/or at least 10 mu A DC H/sup -/ and D/sup -/ ion beams. Of the various proven state-of-the-art polarized ion source technologies, the system recently built and brought into successful operation best meets all needs. In 1989 the authors began acquiring design specifications from TUNL to build HIPIOS (High Intensity Polarized Ion Source). Based on TUNL's experience, HIPIOS should produce in excess of 100 mu A DC H/sup +/ and D/sup +/ ion beams. It employs cold ( approximately 30 K) atomic beam technology, a proven method for generating intense neutral atomic beams. >

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R. Brown

Papers

Status and performance of the IUCF 270 keV electron cooling system

IUCF high intensity polarized ion source

Polarized ion source development at IUCF

The IUCF High Intensity Polarized Ion Source Project

The IUCF high intensity polarized ion source project