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A high voltage, high gradient accelerating column to provide good optics for high current beams has been built and tested by MURA. Design details were chosen to eliminate all possible sparking or corona discharges for reliable high voltage performance. The 12-in. accelerating gap features stainless steel spherical geometry electrodes shaped to produce a converging field. The electrodes are supported by titanium alloy spacers bonded to ceramic rings with a vinyl seal. There are 14 ceramic rings of 14 in. ID, 16 in. OD, and 1-15/32 in. long, giving a column length of 21 in. This column is insulated externally by sulfur hexafluoride gas at three atmospheres absolute pressure confined by a fiber glass pressure shell. The completed column has been tested at 600 kV. Work is being done on ceramic-to-metal seals to eliminate organic materials.

The first three months of operation of the NAL linac after first achieving a 200-MeV beam have been encouraging. The design performance has been achieved at beam intensities of about 20 mA both in the transverse emittance and the momentum spread. Attempts have not been made to go to intensities of 100 mA or greater as yet, and it will be interesting to see how the beam quality is affected by intensity. It is expected that when the linac rf phase and amplitude controls are properly working, the beam quality will be less than the design values. In particular, the momentum spread at the present operating currents is sufficiently small so that a debunching cavity currently is not envisioned. The beam measurements made so far confirm the theoretical results obtained with the PARMILA dynamics program. The particle distributions used in the program are those measured at the entrance to the linac. The large number of components in the systems have lead to concern over the reliability of the linac. The performance over the last three months has dispelled some of this concern. As running periods have increased the failure rate has decreased. Only two major problems stand out at this time. The first is the failure of the spring contacts on the filament leads to the power amplifier tubes. Installation care and the elimination of two of the contact rings which were not water-cooled seem to be providing at least a temporary solution.

At present there are two working injection methods; single-turn using a ferrite kicker magnet and multiturn using a pulsed set of 4 dipoles in one straight section. The operating characteristics of these methods are described. The expected implementation of H injection will involve the incorporation of devices for all three methods in one 6-m long straight section. The H-scheme is described and the expected operating characteristics compared to the present methods.

A 200 MHz Radio Frequency Quadrupole (RFQ) Linac is being designed and constructed for the acceleration of H- ions from 30 keV to 750 keV at a current of 30 mA. The RFQ is being developed as a possible replacement for the Fermilab preaccelerator and as an R and D project to investigate RFQ properties for future accelerators. The current status of the project is described.

The Fermilab Linac uses two electrostatic beam deflection systems as beam choppers, a 750-keV system located between the ion source and the input to the Linac and a 200-MeV system at the output of the Linac. This paper discusses the 750-keV chopper experience with both proton and negative ion beams and the ability of these systems to tailor the Linac beam to the diverse requirements of its users; normal accelerator injection, neutron therapy beam, and electron cooling experiments. This flexibility plus a cleaner beam pulse, improved thyratron operation, and mechanical modularity are the results of recent improvements. Additional benefits have been increased reliability and ease of service to the 750-keV chopper.

This paper reports the dependence of the emittance of the Main Ring injected beam on Booster intensity. The intensity was changed in two different ways: by changing the number of turns injected into the Booster using the normal H- charge-exchange injection and by changing the intensity of the Linac itself by varying the phase of the buncher. The measured emittance of the Linac beam was also compared, assuming adiabatic shrinkage, to the emittance of the Main Ring beam measured while injecting one turn into the Booster.

Successful electron cooling of antiproton beams requires a precisely aligned and high quality electron beam. Mean e- momentum and energy are to be held within 0.25 mrad and ? eV respactively. In addition the e- "temperature" about this mean (rest frame velocity spread) should be held to ?? eV. The diagnostics required to align the beam in angle and energy are rather straightforward. The temperature measuring diagnostics (one for T?; one for T?) are more exotic.