E. A. Heighway

Status of the Chalk River Superconducting Heavy-Ion Cyclotron

A K = 520 superconducting cyclotron using the Chalk River 13 MV tandem accelerator as an injector is being designed to accelerate all ions from Li (to 50 MeV/u) to U (to 10 MeV/u). The cyclotron will considerably upgrade the Chalk River accelerator facility. The basic design of the cyclotron remains unchanged but details of trim rods, injection and extraction arrangements have changed and other features have become firm. Full scale modelling of the magnet and radiofrequency accelerating system is proceeding concurrently with the cyclotron design; the status of both is reported.

The Chalk River Superconducting Cyclotron

The Chalk River K=520, 4-sector, superconducting cyclotron1, is designed to accelerate all ions from Li (to 50 MeV/u) to U (to 10 MeV/u) using a 13 MV tandem as injector. Concurrent with the design of the integrated accelerator facility we have been testing major components - specifically the radiofrequency accelerating structure and the cyclotron magnet. The project has now been approved and site preparation is underway. This paper reports on the cyclotron assembly, initial cooldown of the cryostat and first magnetic field measurements.

A First Order Space Charge Option for TRANSOPTR

TRANSOPTR, a beam transport design code, incorporates autoriatic optimization of a beam transport system under general constraints. This optimization can be performed for either first order (with or without space charge effects) or second order calculations. Space charge effects are calculated in the x-y plane for continuous beams or in x-y-z space for bunched beams using a new approach. The method integrates a set of differential equations describing the evolution of the ¿ bean matrix along the main trajectory where the ¿ matrix represents the beam ellipsoid in phase space. A spatially uniform charge density approximation is used and emittance growth is assumed to be negligible. Changes in the optimumn beam transport conditions of a system caused by space charge effects can be readily evaluated with this code. Some applications of the code are given.

Double Pass Linear Accelerator - Reflexotron

Measurements of energy spectra and percentage beam transmissions are given for an S-band linear accelerator through which the electron beam passes twice, in opposite directions. Results are presented for two magnet reflecting systems which have energy acceptance windows, ¿E/E, of 2% and 16% where E is the output beam energy after the first pass through the accelerator. For a first pass beam energy of 8 MeV the second pass energy could be varied from 3 MeV to 16 MeV by changing the separation between the accelerator and the magnet system. The corresponding full-width half-maximum energy spreads were 1.6 MeV and 0.7 MeV respectively. The system transmission was 35% first pass (unbunched injected beam) and ~ 100% second pass.

First operation of the Chalk River superconducting cyclotron

Abstract Successful development of the first beam from the Chalk River superconducting cyclotron has verified the design and construction of all elements of the cyclotron.

Movable Steel Trim Rods and the Orbit Dynamics of the Chalk River Superconducting Heavy Ion Cyclotron

Trim rods rather than trim coils have been chosen to isochronize the magnetic field. These provide good isochronism and the tolerances associated with the rods are acceptable. For low specific-energy high-mass ions, regions where ¿r approaches unity have been studied in detail. The rods can readily remove unwanted error field components.

A program for automatically matching the emittance and dispersion of the beam injected into the Chalk River superconducting cyclotron

Abstract Matching the MP tandem beams to the cyclotron requires the calculation of 23 parameters, 7 of which are dependent on the beam phase space. All parameters must be redetermined for each ion-energy combination. A program called CYCMATCH has been written which, given the cyclotron injection transfer matrix and the 6-dimensional beam emittance from the MP tandem, uses a 9-step procedure to calculate the 23 parameters. Details of the optical and numerical procedures are described.

First Operation of the TASCC Beam Bunching System

The Chalk River Tandem Accelerator Superconducting Cyclotron (TASCC) system uses a low-energy buncher (LER) and a high-energy rebuncher (HER) to prodtice the required bunched beam at the cyclotron injection stripper foil. The LEB modulates the < 300 keV beam from the negative ion source with a f¿undamental plus 2nd harmonic approximation to an ideal saw tooth to give a time focus at the stripper in the tandem accelerator terminal. The HEB, operating at the 2nd or 4th harmonic, corrects for debunching after the stripper and produces a new time focus at the cyclotron stripper. Transit time jitter through the tandem accelerator is corrected by a phase stabilizing circuit using both energy analysis after the HEB and a correlation with a capacitive phase probe signal . In the first experiments with a low energy 12C beam, the LEB produced bunch lengths of about 1.6 ns and the HEB produced the expected energy dispersion. Beam tests will be described.

Supergoblin the Accelerated Orbit Code in Use for the Chalk River Superconducting Cyclotron

SUPERGOBLIN is a general cyclotron orbit code of distinguished lineage having reached Chalk River via Oak Ridge, Michigan State and TRIUMF. Several new features have been added to aid in cyclotron design and analysis. Features described are a treatment of spiral dees, a second order transport matrix option, phase-space projection tracking, an automatic injection matching algorithm, a method of treating the extraction system and parameter search and fitting options.

The Beam Bunching System for the Chalk River Superconducting Cyclotron

The bunching system for the tandem accelerator-superconducting cyclotron is of the buncher-rebuncher type. It consists of a low energy gridded buncher before the tandem that produces a time focus at the tandem stripper, combined with a high energy buncher between the tandem and the cyclotron to correct for debunching of the beam produced by energy straggling in the stripper. To meet the cyclotron design energy resolution of 5:10<4 the bunch length produced at the cyclotron has to be less than three degrees in rf phase.