[en] The optically pumped polarized H^- ion source at TRIUMF produces up to 100 μΑ dc of 78% polarized beam within an emittance of 1.0 π mm mrad and is now being prepared for an upcoming experiment at TRIUMF that will measure parity violation in pp scattering at 230 MeV. The optical pumping is accomplished by argon laser pumped Ti-sapphire lasers. The laser control system provides monitoring and precision control of the lasers for fast spin reversal up to 200 s^-1. To solve the problems of laser power and frequency stabilization during fast spin flipping, techniques and algorithms have been developed that significantly reduce the variation of laser frequency and power between spin states. The upgraded Faraday rotation system allows synchronous measurement of Rb thickness and polarization while spin flipping. The X Window environment provides both local and remote control to laser operators via a local area network and X window terminals. In this new environment issues such as access authorization, response time, operator interface consistency and ease of use are of particular importance. (author)

[en] A novel phenomenon of high frequency modulated electron beam generation is presented. Experiment was carried out with an electron diode having active source of the cathode plasma. Modulated electron beam with duration of > 1μs was generated during more than one hour with a frequency of 2Hz. The frequency of the modulation was found to be > 325MHz. The modulation of the beam current amplitude reaches > 30%. The generation of the modulated electron beam is accompanied by electromagnetic radiation with the same frequency and power of several tens of kW. Based on the experimental data a qualitative model of the observed phenomenon is described

[en] Ultrashort x-ray pulses permit observation of fast structural dynamics in a variety of condensed matter systems. The authors have generated 300 femtosecond, 30 keV x-ray pulses by 90 degrees Thomson scattering between femtosecond laser pulses and relativistic electrons. The x-ray and laser pulses are synchronized on a femtosecond time scale, an important prerequisite for ultrafast pump-probe spectroscopy. Analysis of the x-ray beam properties also allows for electron bunch characterization on a femtosecond time scale

[en] The EBIS (electron beam ion source) sources have been invented to produce highly charged ions to inject into accelerators. Recent studies based on the interaction between highly charged ion beams and surfaces from semiconductors and isolators draw new prospects about the industrial applications of EBIS sources. (A.C.)

[en] At Brookhaven National Laboratory, an Electron Beam Ion Source (EBIS) is operational and has produced charge states such as N⁷⁺, Ar¹⁶⁺, and Xe²⁶⁺ using neutral gas injection. Ions such as Na⁷⁺ and Tl⁴¹⁺ have been produced using external ion injection. The BNL EBIS effort is directed at reaching intensities of interest to RHIC, approximately 3 x 10⁹ particles/pulse which will require EBIS electron beams on the order of 10A. Pulsed electron beams up to 1.14 A have been produced using a 3mm LaB₆ cathode. Ion yields corresponding to 50% of the maximum trap capacity for electron beams up to 0.5A have been obtained. The goal for the TestEBIS is to produce a uranium ion charge state distribution peaks at U⁴⁵⁺ with 50% of the trap capacity for a 1A electron beam

[en] A duoplasmatron ion source is used to produce 25 mA of ³He+ with a pulse width of ∼80 ms at 360 Hz for acceleration to 10.5 MeV. At this energy, ³He striking water or carbon targets can produce short lived isotopes of ¹¹C, ¹³N, ¹⁵O and ¹⁸F for medical positron emission tomography (PET). A duoplasmatron ion source was chosen originally since it is capable of a sufficient singly-charged helium beam with an acceptable gas consumption. Stable long-term operation of the source required a change in the filament material to molybdenum, and a careful understanding of the oxide filament conditioning, operation and geometry. Other improvements, particularly in the electronics, were helpful to increasing the reliability. The source has operated for many months at ∼2.5% duty factor without significant problems and with good stability. We report here the effort that was done to make this source understandable and reliable

[en] The radioactive ion beams that will be delivered by the SPIRAL facility will be produced by the interaction of a stable high energy and high intensity primary ion beam delivered by the GANIL cyclotrons with a carbon target heated to 2000 deg C. During this interaction, some radioactive atoms will be created and will diffuse out of the target before entering into an electron cyclotron resonance ion source where they will be ionized and extracted. The production of radioactive ion beams with this method implies high radiation fields that activate and can damage materials located in the neighborhood of the target. Therefore, the production system which is composed of the permanent magnet ECR ion source coupled to a graphite target will be changed after two weeks of irradiation. As this ensemble will be very radioactive, this operation has to be supervised by remote control. The radiation levels around the target-ion source system and a detailed description of the different precautions that have been taken for safety and for prevention of contamination and irradiation are presented. (author)

[en] A 110-mA, 75-keV dc proton injector is being developed at Los Alamos. We use a microwave proton source coupled to a two solenoid, space-charge neutralized, low-energy beam transport (LEBT) system. The ion source produces 110-mA proton current at 75 keV using 600 - 800 W of 2.45 GHz input discharge power. Typical proton fraction is 85-90% of the total extracted ion current, and the rms normalized beam emittance after transport through a prototype 2.1 m LEBT is 0.20 (πmm-mrad). Beam space-charge neutralization is measured to be > 98% which enables the solenoid magnetic transport to successfully match the injector beam into a radio-frequency quadrupole (RFQ). Beam simulations indicate small emittance growth in the proposed 2.8 m low-energy demonstration accelerator (LEDA) LEBT. The LEBT also contains beam diagnostics, steering, and a beam deflector for variable duty factor and accelerator fast protect functions. The injector computer controls and reliability status are also discussed

[en] The structure and the material of cathodes for a PIG ion source of an AVF cyclotron have been studied. A versatile test stand is used to obtain data on arc voltage and current for various source conditions. Arc impedances are compared for two cathode structures: well cooled and poorly cooled cathodes. The sputtering rate and the temperature of the cathodes are measured by varying the gas flow rate of the source. The well cooled cathode has a 60% higher negative impedance than the poorly cooled cathode. This structure is suitable for a stable source. Long source life is assured by this sophisticated cathode structure which is helpful for maintaining the cathode stabilized at a temperature of 1750deg C. On the other hand, that structure is more favorable for getting ions of a higher charge state. These specifications are established by comparing the yield of accelerated ions such as ¹⁴N^3+,4+,5+ for the PIG ion source of the RCNP AVF cyclotron. Several high melting point materials such as niobium, tantalum, tungsten (pure and porous) and molybdenum alloy (TZM) have been investigated as a cathode. These material studies suggest that the arc voltage varies in each material from 300 to 600 V and that it has different sputtering rates, from 0.25 to 1.0 g/h. Cathodes of molybdenum alloy indicate the possibility that these cathodes, with various compositions, can work at the desired arc voltage for a PIG ion source. (orig.)

[en] The combination of intense neutron pulses from the LANSCE or ISIS sources with modern detectors of neutron currents, has allowed work to begin on exciting new experiments using single neutron pulses. To illustrate this field we shall describe three applications which make use of the transmission of neutron through a sample as a function of their energy. The three examples are (i) the measurement of the temperature along the body of a projectile after launching, (ii) a stroboscopic study of the warming cycle of a jet engine at full power and (iii) the study of phase transitions under extreme conditions. To prepare for experiments of this kind a 40 m special flight path is being built at LANSCE, and preliminary experiments to demonstrate the method have been made with an existing 10 m path. (author)