P. Miller

Design, construction, and first commissioning results of superconducting source for ions at NSCL/MSU.

A new electron cyclotron resonance ion source (ECRIS) was constructed at the NSCL/MSU to replace the existing SC-ECRIS. This ECRIS operates at 18+14.5 GHz microwave frequencies with a planned upgrade to 24-28 GHz in the second phase of commissioning. A superconducting hexapole coil system produce the radial magnetic field; the axial trapping is produced with six superconducting solenoid coils enclosed in an iron yoke to allow the optimization of the distance between the plasma electrode and the resonant zone in the plasma. We report the details of the design, construction, and initial commissioning results of this new ECRIS.

Status report on the design and construction of the Superconducting Source for Ions at the National Superconducting Cyclotron Laboratory/Michigan State University

A status report of the design and fabrication of a new, fully superconducting electron cyclotron resonance ion source will be presented. The Superconducting Source for Ions (SuSI) first will operate at 18+14.5GHz microwave frequencies. A short description of the magnet structure and the injection and extraction hardware will be presented. Several innovative solutions are described, which will allow maximum flexibility in tuning SuSI in order to match the acceptance of the coupled cyclotrons. Details of an ultrahigh temperature inductive oven construction are given as well as a description of the low-energy beam transport line.

A Comparison of Electrostatic and Magnetic Focusing of Mixed Species Heavy Ion Beams at NSCL/MSU

Experience at the National Superconducting Cyclotron Laboratory has shown the first focusing element after the electron cyclotron resonance ion source (ECRIS), before the beam is analyzed by a magnetic dipole, to be critical to subsequent beam transport and matching. Until 2004, both ion sources at the NSCL used a solenoid as this first focusing element. Observation of hollow beam formation led to further analysis and the decision to replace the solenoid with an electrostatic quadrupole triplet on a test basis [1]. Substantial increases in net cyclotron output were achieved, leading us to adopt electrostatic quadrupole focusing as the permanent configuration. In addition, a sextupole magnet was installed in this beam line. Motivations for these changes and results of operating experience are discussed.

Design of SuSI — Superconducting Source for Ions at NSCL/MSU — I. The Magnet System

An ECR ion source is being designed to initially serve as a test bench for development and later will replace the existing 6.4 GHz SC‐ECRIS. This ECRIS will operate at 18+14.5 GHz microwave frequencies. The radial magnetic field will be produced by a superconducting hexapole coil, capable of 1.5 T at the aluminum plasma chamber wall (R=50 mm). The axial trapping will be produced with six superconducting solenoids enclosed in an iron yoke. We will present the Flexible Axial Magnetic Field Concept, introduced for the first time in this design, which will allow tuning the distance between the plasma electrode and resonant zone in the plasma. The distance between the two axial magnetic maxima will be also tunable in the range of 340 to 460 mm.

Absolute Calibration of Dee Voltage by X-Ray Endpoint

We describe an X-ray technique for calibrating the rf voltmeters used to measure and stabilize the potentials of the dees in the M.S.U. cyclotron. The method is generally applicable and should be especially useful in cyclotrons which have multiple dees or which do not have separated turns.

Emittance studies of ARTEMIS-the new ECR ion source for the coupled cyclotron facility at NSCL/MSU

In order to match the acceptance of the coupled cyclotrons as well as the beam intensity requirements, the emittance and the brightness of the new Electron Cyclotron Resonance ion source built for the Coupled Cyclotron Project at NSCL/MSU (Advanced Room TEMperature Ion Source-ARTEMIS), was optimized for several ion source parameters: microwave power, bias disk voltage, plasma aperture-puller aperture gap distance, puller electrode voltage, gas pressure, and axial magnetic field intensity. The emittance was measured with a simple setup composed from a screen with parallel slits and a NEC rotary wire scanner connected to a digital oscilloscope and a PC. The present study was done only for ions produced from gases, a radial insertion micro-oven capable of reaching 1500 °C is under construction.