Search results for "Gun"
showing 10 items of 494 documents
The dynamics of bunched laser-cooled ion beams at relativistic energies
2007
We discuss the axial dynamics of laser-cooled relativistic C3+ ion beams at moderate bunching voltages. Schottky noise spectra measured at a beam energy of 122 MeV/u are compared to simulations of the axial beam dynamics. Ions confined in the bucket are addressed by the narrow-band force of a laser beam counter-propagating to the ion beam, while the laser frequency is detuned relatively to the cooling transition frequency in the rest frame of the bucket. At large detuning comparable to the momentum acceptance of the bucket, the axial dynamics can be well explained by the secular motion of individual non-interacting ions. At small detuning, corresponding to a small axial momentum spread Δpax…
Oscillations of ECR ion source beam current along the beam transport of the JYFL K-130 cyclotron
2013
A versatile measurement system has been developed to study the temporal characteristics of ion beams in millisecond time scale. The system is composed of data acquisition hardware and LabVIEW based measurement and analysis program. The measurement system and ion beam current oscillation results measured with a 14 GHz AECR-U type ion source at University of Jyv"askyl"a, Department of Physics (JYFL), are presented. It is shown that the ion beams exhibit periodic current fluctuations at frequencies from 100 Hz to 1.5 kHz with amplitudes ranging from 1 to 65 percent of the average beam current. It is argued that these oscillations originate from the ion source plasma since their characteristics…
Ion beam preparation of 7Li+ for precision experiments at heavy ion storage rings
1997
Abstract Heavy ion storage rings allow for tests of the structure of local space time via the Doppler effect. At the TSR/Heidelberg an experiment with high resolution laser spectroscopy at 7 Li + is performed. To gain the maximum resolution for saturation spectroscopy new methods of relativistic ion beam preparation and diagnostics have been developed. The laser cooling of the beam allows for precision determination of the mean velocity of the ions. A novel phase synchronous detection scheme, ultimately sensitive to single ions, gives insights into the cooling mechanism and dynamics. With an additional synchronous excitation scheme systematic uncertainties of the test experiment can be dras…
A linear radiofrequency quadrupole ion trap for the cooling and bunching of radioactive ion beams
2000
A linear radiofrequency quadrupole ion guide and beam buncher has been installed at the ISOLTRAP mass spectrometry experiment at the ISOLDE facility at CERN. The apparatus is being used as a beam cooling, accumulation, and bunching system. It operates with a buffer gas that cools the injected ions and converts the quasicontinuous 60- keV beam from the ISOLDE facility to 2.5-keV beam pulses with improved normalized transverse emittance. Recent measurements suggest a capture efficiency of the ion guide of up to 40% and a cooling and bunching efficiency of at least 12% which is expected to still be increased. The improved ISOLTRAP setup has so far been used very successfully in three on-line e…
A highly selective laser ion source for bunched, low emittance beam release
2004
A novel type of resonance ionization laser ion source (RILIS) is under development, which combines the advantages of laser ionization with those of a source-implemented ion trap. This laser ion source trap (LIST) system, based on a gas-filled linear radio-frequency quadrupole ion trap, decouples the evaporation and ionization process by introduction of a primary surface ion repeller. Apart from significantly enhancing the selectivity in radioactive ion beam production, optimum control on the temporal pulse structure and the emittance of the generated laser ion bunch is obtained. A variety of operational modes from quasi-dc to microseconds-bunched ion beams with variable repetition rate can …
First results with the yin-yang type electron cyclotron resonance ion source
2007
Abstract Highly charged heavy-ion beams are often produced with Electron Cyclotron Resonance Ion Sources (ECRIS). The so-called conventional minimum-B ECRIS design includes two solenoid magnets and a multipole magnet (usually a hexapole). A minimum-B configuration can also be formed with “yin-yang” (“baseball”) type coils. Such a magnetic field configuration has been extensively tested in magnetic fusion experiments but not for the production of highly charged heavy ions. The application of the afore-mentioned coil structure to the production of multiply charged ion beams was studied. In this paper we present a design of a yin-yang type ion source known as the ARC-ECRIS and some preliminary…
Bunching and cooling of radioactive ions with REXTRAP
2002
The properties of radioactive ion beams produced by the present on-line target ion source technology are often not suitable for direct post acceleration. For that purpose pulsed and cooled beams of higher charged ions are required. In the case of REX-ISOLDE, the post accelerator at the CERN-ISOLDE radioactive beam facility, a unique system for beam preparation is used. It consists of a gas-filled cylindrical Penning trap (REXTRAP) for bunching and cooling followed by an electron beam ion source for charge state breeding. The Penning trap has been successfully operated with an efficiency of up to 40% and a total number of up to 107 ions stored. Buffer-gas sideband cooling at the ions’ cyclot…
Variation of physical constants and electron–positron oscillations: Zitterbewegung in a plane wave
2021
The space and time dependence of physical constants is currently a debated issue for experimental findings, and theoretical reasons seem to indicate that this is not a mere speculative possibility. The paper provides a relativistic description of a free fermion evolving under the assumption of temporal variation of the physical constants. The assumed generalisation of the Dirac equation is particularly simple and permits a grouping of the constants in one single parameter and a consequent agile treatment of the problem. The form of the equations suggests a rescaling of the temporal coordinate $$x^0=ct$$ which allows a plane wave solution. Two are the main results of the treatment. First, th…
Shadowing of the operating mode by sidebands in gyrotrons with diode-type electron guns
2021
In gyrotrons operating in high-order modes, during the startup process, the shadowing of the operating mode by two sidebands may take place. By “shadowing,” we mean the situation when, during the voltage rise, one of the parasitic modes is excited first, and this excitation prevents the excitation of the desired mode. Then, the oscillations of the first parasitic mode, whose frequency is higher than the frequency of the desired operating mode, can be replaced by excitation of the second parasitic mode, whose frequency is lower than the operating one. As a result, the desired mode remains in the “shadow” of these parasitic modes and is never excited. This paper describes such effect in gyrot…
Sagunt vint-i-cinc anys després de la reconversió: cap a un model industrial de gran empreses foranes i pimes
2008
El cuarto de siglo transcurrido desde el cierre de la cabecera siderúrgica ha sido testigo de un cambio muy profundo en la realidad económica saguntina. De una economía y un pueblo (el Puerto de Sagunto) que pivotaban alrededor de una factoría siderúrgica se ha pasado a una realidad mucho más compleja desde la doble perspectiva social y económica,donde coexisten un núcleo de grandes establecimientos industriales de firmas multinacionales y nacionales con un creciente número de PYMES industriales y terciarias de origen valenciano y local. De igual modo, el terciario avanzado constituye hoy una realidad pujante donde hace tan sólo tres lustros no era sino una actividad testimonial. La socieda…