A U.S./Russian collaboration of accelerator scientists was directed to the development of high averaged-current (∼1 mA) and high-quality (emittance ∼15 πmm mrad; energy spread ∼0.1%) 1.75 MeV proton beams to produce active interrogation beams that could be applied to counterterrorism. Several accelerator technologies were investigated. These included an electrostatic tandem accelerator of novel design, a compact cyclotron, and a storage ring with energy compensation and electron cooling. Production targets capable of withstanding the beam power levels were designed, fabricated, and tested. The cyclotron/storage-ring system was theoretically studied and computationally designed, and the electrostatic vacuum tandem accelerator at BINP was demonstrated for its potential in active interrogation of explosives and special nuclear materials.

A summary of the work performed to date is presented. The project brings together accelerator scientists in the US and Russia to develop high-current charged-particle accelerators for applications to explosives detection. These include an electrostatic tandem accelerator of novel design and a compact cyclotron and storage ring with energy compensation and electron cooling.

The Al'fa irradiation complex has been developed and built at the Joint Institute of Nuclear Research. The purpose of this complex is to irradiate polymer films used in the production of track memebranes. The complex contains an isochronous cyclotron with external ion injection, a system for extracting and transporting accelerated ions, and an irradiation setup for the initial material – a polyethylene film. The Al'fa irradiation complex can produce track membranes from polyethyleneterephtalate (lavsan) up to 25 μm thick and up to 40 cm wide.

This paper examines possible variants of the beam particle extraction from the sector cyclotron with an efficiency near 100%. Requirements for tolerances and stability of the magnetic and accelerating high frequency fields of the cyclotron are presented. The necessity of the flat-top acceleration regime is proved. It is concluded that the use of the closed orbit expansion effect for the beam extraction from the sector cyclotron has advantages in what concerns the increase in the efficiency of the set-up as a whole.

A full-scale prototype of the accelerating cavity for the superconducting deuteron sector cyclotron at the energy of 100 MeV is described. The fundamental frequency and the distribution of the radio frequency voltage along the accelerating gap were calculated by the RFC3D program for computing 3D components of the electromagnetic field. The RF measurements proved the validity of the calculations with an accuracy better than 5% for the cavity fundamental and 10% for the voltage.<>

The theoretical and experimental study of beam extraction method using the closed orbit expansion effect is described. The steep slope of the magnetic field variation magnitude is used to change the momentum compaction factor for the limit radial area. The orbit separation is found by computing the dynamical equations, since the behaviour of the betatron oscillation frequencies and the beam phase are investigated in this radial region. The experimental study of the effect is carried out with the ring cyclotron electron model, which is a strong focusing eight sector isochronous cyclotron. Calculated orbit separation in the extraction area is about 2+4 cm. The magnet system which is to obtain the proper gradient of the magnetic field variation and the magnet measurements results are described. The measured value of the orbit separation equals 4 cm. At the same time the space between two orbits without current (free of particles) is about 2 cm and the full current on the separated orbit is equal to that before separation. The theoretically predicted beam phase shift is found to be equal to 30+40°. The obtained results confirm the possibility of the 100% beam extraction from the accelerator with space magnetic field variation.

A 1 MeV proton injector of the ring-shaped phasotron model, designed and constructed at the Laboratory of Nuclear Problems at Dubna in 1960–1962 is described. Protons are accelerated in the gap of a toroidal cavity excited on the basic frequency of about 60 MHz by a self-excited oscillator. A cold cathode of the Penning discharge type is used as an ion source. Proton current of 10 mA per 20 μsec pulse is supplied by the injector at the repetition rate of 50 Hz.

BS>The capture of particles and their phase shift to a finite radius during the acceleration process must be taken irto consideration when analyzing the characteristics of the phasotron; the frequency and the amplitude of the accelerating voltage needed to accelerate the particles to their ultimate radius must be at their maximum. These characteristics of the phasotron of the Joint Institute for Nuclear Studies were determined during 1961/62. The proton energies were measured as functions of the orbital radius and of the potential field of the duant of the ion source and of the accelerating chamber of the phasotron. On the basis of the results obtained, it was found possible to provide simultaneously optimal conditions for both the capture and the acceleration of the proton beam to its ultimate radius without phase loss. The data indicated that the value of the accelerated proton flux at the ultimate radius was increased from 0.3 to 1.1 to 1.2 mu amp. (TTT)

A pulsed ion source with a Penning discharge that uses a cold aluminum cathode is described. The characteristics of the power supply system for the ion source are described. An analysis of the beam focusing system is given, and results of an investigation of the dependence of the ion current on the various parameters of the ion source are presented. (tr-auth)

This article describes the results of research conducted during 1961 and 1962 on tailoring the highfrequency characteristics of the six-meter synchrocyclotron at the Dubna Joint Institute for Nuclear Research. The results obtained enabled us to simultaneously optimize capture conditions and accelerate the proton beam to the ultimate radius with virtually no phase losses. As a result, thecurrent of accelerated protons at the ultimateradins was increased from 0.8 to 1.1–1.2 μ A.