D. Wolff

Tevatron Electron Lenses: Design and Operation

The beam-beam effects have been the dominating sources of beam loss and lifetime limitations in the Tevatron proton-antiproton collider [1]. Electron lenses were originally proposed for compensation of electromagnetic long-range and head-on beam-beam interactions of proton and antiproton beams [2]. Results of successful employment of two electron lenses built and installed in the Tevatron are reported in [3,4,5]. In this paper we present design features of the Tevatron electron lenses (TELs), discuss the generation of electron beams, describe different modes of operation and outline the technical parameters of various subsystems.

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.

MECAR (Main Ring Excitation Controller And Regulator): a real time learning regulator for the Fermilab Main Ring or the Main Injector synchrotron

The real-time computer for controlling and regulating the FNAL (Fermi National Accelerator Laboratory) Main Ring power supplies has been upgraded with a new learning control system. The learning time of the system has been reduced by an order of magnitude, mostly through the implementation of a 95-tap FIR filter in the learning algorithm. The magnet system consists of three buses, which must track each other during a ramp from 100 to 1700 A at a 2.4 s repetition rate. This paper presents the system configuration and the tools used during development and testing.

Energy Saver Partial Ring Power Tests

As installation of the Energy Saver progresses, completed sections of the ring are operated to test subsystems and their interactions. This paper describes the power and quench protection tests in the 1/8 ring operation (3/4 of A sector) completed in June, 1982, and in the more recent 1/3 ring operation of E and F sectors.

Operational aspects of the main injector large aperture quadrupole (WQB)

A two-year Large Aperture Quadrupole (WQB) Project was completed in the summer of 2006 at Fermilab. [1] Nine WQBs were designed, fabricated and bench-tested by the Technical Division. Seven of them were installed in the Main Injector and the other two for spares. They perform well. The aperture increase meets the design goal and the perturbation to the lattice is minimal. The machine acceptance in the injection and extraction regions is increased from 40pi to 60pi mm-mrad. This paper gives a brief report of the operation and performance of these magnets. Details can be found in Ref [2].

Tevatron Beam-Beam Compensation Project Progress

In this paper, we report the progress of the Tevatron Beam-Beam Compensation (BBC) project [1]. Proton and antiproton tuneshifts of the order of 0.009 induced by electron beam have been reported in [2], suppression of an antiproton emittance growth in the Tevatron High Energy Physics (HEP) store has been observed, too [1]. Currently, the first electron lens (TEL1) is in operational use as the Tevatron DC beam cleaner. Over the last two years, we have greatly improved its reliability. The 2nd Tevatron electron lens (TEL2) is under the final phase of development and is being prepared for installation in the Tevatron in 2005.

Magnet Protection Using ZNR Surge Suppressors

In the Fermilab Main Ring power supply system, we have added ZNR type (zinc oxide nonlinear resistor) suppressors to each power supply terminal to limit the magnet voltage-to-ground to 2.1 kV. The ZNRs conduct 50 A at the 2.1 kV clipping voltage, and leak less than 1 mA at the 1.5 kV maximum operating voltage. Their repetitive surge rating is 1.4 kJ. Their main advantage, in comparison to spark gaps, is that the ZNRs do not break down and cause transients and high voltages at neighboring points on the magnet bus.

Protection of Hardware: Powering Systems (Power Converter, Normal Conducting, and Superconducting Magnets)

Along with the protection of magnets and power converters, we have added a section on personnel protection because this is our highest priority in the design and operation of power systems. Thus, our topics are the protection of people, power converters, and magnet loads (protected from the powering equipment), including normal conducting magnets and superconducting magnets.

A solid state Marx generator for TEL2

The solid-state Marx generator modulates the anode of the electron gun to produce the electron beam pulses in the second Tevatron Electron Lens (TEL2). It is capable of driving the 60 pF terminal with 600 ns pulses of up to 6 kV with a p.r.r. of 50 kHz. The rise and fall times are 150 ns. Stangenes industries developed the unit and is working on a second version which will go to higher voltage and have the ability to vary its output in 396 ns intervals over a 5 mus pulse.