J. McCarthy

Very High Precision Current Regulated Power Supplies for the Fermilab Antiproton Source

These Power Supplies were designed to power the accumulator and debuncher storage rings at the Fermi National Accelerator Laboratory Antiproton Source. The accumulator and debuncher are both large acceptance 8 GeV storage rings. The accumulator ring has the most stringent requirements since it will be required to store beams for periods in excess of twenty four (24) hours. In order to ensure long term beam stability, resonances up to order eleven (11) must be avoided. Because of this stringent tuned stability requirement, the power supplies which power the three main quadrupole and the main dipole busses must be extremely stable. Thus the current regulation specification for these power supplies is 10 PPM (0.001%) including differential and common mode ripple, long term drift, and line and load regulation.

Mechanical and Electrical Design of the Fermilab Lithium Lens and Transformer System

A lithium lens focusing device will be used for the collection of 8 GeV antiprotons in the Fermilab Tevatron I Project. The details of the mechanical and electrical design of the Fermilab lens and its associated toroidal transformer are discussed. The lens, with a radius of 1 cm and length 15 cm, is expected to achieve gradients of 1000 T/m for a focal distance of 0.225 m. The gradient requires a current on the order of 5x105A, resulting in large electromagnetic and thermal stresses. The power supply discharge current and the effect of the inductance of the power leads and connections are minimized by the use of a toroidal matching transformer surrounding the lens itself.

Kickers and Power Supplies for the Fermilab Tevafron I Antiproton Source

The Fermilab Antiproton Source Accumulator and Debuncher rings require 5 kickers in total. These range in design from conventional ferrite delay line type magnets, with ceramic beam tubes to mechanically complex shuttered kickers situated entirely in the Accumulator Rings 10-10 torr vacuum. Power supplies are thyratron switched pulse forming networks that produce microsecond width pulses of several kiloamps with less than 30 nanoseconds rise and fall times. Kicker and power supply design requirements for field strength, vacuum, rise and fall time, timing and magnetic shielding of the stacked beam in the accumulator by the eddy current shutter will be discussed.

The TEV I Beam Position Monitor System

The TeV I Beam Position Monitor System is described. This system is designed to provide accurate orbit information during both the commissioning and operational phases of the Fermilab Antiproton Source. The system is required to provide position information with submillimeter resolution for both single turn orbit measurements with beam intensities in the range 1×109 to 1×1011, and multiple turn (closed orbit) measurements with beam intensities in the range 1×107 to 5×1011. The system has already been used during commissioning of the Debuncher to measure the first turn through the ring, the horizontal and vertical betatron tunes, the closed orbit, the dispersion, aperture, and chromaticity. During normal antiproton operation the system will be used to monitor beam position throughout the accumulation process.

Quasi-Optimal Algorithms for the Control Loops of the Fermilab Energy Saver Satellite Refrigerator

The Cryogenic System of the Satellite Refrigerator for the Energy Saver Accelerator Ring comprises 12 interrelated closed loops and several open loops. A quasi-optimal algorithm to control the Cryogenic System, under different modes operation, is described. The constraints imposed to define these algorithms and the process followed to characterize the functional parameters are described. A report on the results obtained with the algorithms in a test facility will be presented.

Power tests of the Fermilab Lithium Lens for antiproton collection

A prototpye Lithium Lens to be used for the collection of antiprotons in the Fermilab Tevatron I project has been constructed. Some of the fabrication details, the procedure for lithium filling and the results of the initial operation are discussed.

The Microprocessor-Based Control Facility of the He Refrigerator System Used in the 1000 GeV Fermilab Switchyard

Because of Fermilabs early commitment to computer control and monitoring, several very large control systems have evolved. The continually expanding size of these systems has begun to tax some of the central computers almost to their limits. These limitations of the central system became very visible when a helium liquefier system that would provide the necessary cryogenics for the upgrading of the Fermilab Switchyard to 1000 GeV needed to be incorporated into the existing Switchyard control system. The control and monitoring requirements of the refrigeration system were of such a nature that distributed processing became an attractive way to alleviate the overloading of the central computer that the helium liquefier would have presented. The purpose of this paper is to give a description of the hardware and software that were necessary to implement the distributed processing concept.

Proton Extraction and Transport for Pbar Production in Tevatron I

The design, fabrication, and commissioning of the extraction and beam transport systems required for pbar production for the FNAL Antiproton Source will be described. The extraction system utilizes a fast kicker and Lambertson septum magnets to extract in a single turn one booster batch of 120 GeV protons from the FNAL Main Ring. The extracted beam is transported a distance of 174 m by a beam transport system consisting of 12 dipoles and 14 quadrupoles. The last 8 quadrupoles are configured as 4 pairs which focus the beam to a small round spot (radius 0.4 mm) on a pbar production target. The extraction channel is also designed to inject 8 GeV cooled pbars from the Accumulator Ring into the Main Ring, or extract 8 GeV protons from the Main Ring for diagnostic and tune-up work in the Antiproton Source beam lines and rings.

Magnet Current Bypass Shunt

A precision active shunt has been developed for fine tuning of individual magnet fields in a series magnet string operated from a single power supply. The shunt uses power transistors operated in linear mode to regulate the bypass current in the range 0 to 50 A with precision of ±10 mA. Communication with and control of shunt which may be floating 1000 V or more above earth ground, is by means of transformer coupled isolation amplifiers. Because of reliability requirements, 7 transistors, mounted on demountable water cooled copper plate are used. Low level electronics and current sensing resistor are mounted on the same plate. This paper presents system description and preliminary results.

Large Dynamic Range Beam Profile Measurement in a High Background Environment

Beam profile measurements using a scanning target and loss monitor in the Fermilab Main Ring extraction channel have long proved their usefulness as a diagnostic method in analyzing extraction problems. To extend these measurements to a sensitivity greater than in the present system a different technique has been employed. A simple three element particle telescope viewing the scanning target allows a sensitive measurement of the tail on the edges of the beam profiles as well as the relative particle densities of the extracted beam and the circulating beam in the Main Ring. Both these regions are of significant interest in understanding extraction losses. The details of the profile measurement technique, some results using the telescope and possible methods of improving the measurements are discussed.