Ion Beam Diagnostics Research Articles

Profilometer of secondary beams based on a multiwire proportional chamber

A profilometer for diagnostics of secondary ion beams with Z ≥ 2 is described. Two methods of beam profile measurements are compared: a counting method, when pulses from each particle are registered, and a current method with channel-by-channel measurement of the integral current. The counting characteristics and the lifetimes of the profilometer for these methods of beam profile measurements are compared.

Results of Joint Experiments and other IAEA activities on research using small tokamaks

This paper presents an overview of the results obtained during the Joint Experiments organized in the framework of the IAEA Coordinated Research Project on ‘Joint Research Using Small Tokamaks’ that have been carried out on the tokamaks CASTOR at IPP Prague, Czech Republic (2005), T-10 at RRC ‘Kurchatov Institute’, Moscow, Russia (2006), and the most recent one at ISTTOK at IST, Lisbon, Portugal, in 2007. Experimental programmes were aimed at diagnosing and characterizing the core and the edge plasma turbulence in a tokamak in order to investigate correlations between the occurrence of transport barriers, improved confinement, electric fields and electrostatic turbulence using advanced diagnostics with high spatial and temporal resolution. On CASTOR and ISTTOK, electric fields were generated by biasing an electrode inserted into the edge plasma and an improvement of the global particle confinement induced by the electrode positive biasing has been observed. Geodesic acoustic modes were studied using heavy ion beam diagnostics on T-10 and ISTTOK and correlation reflectometry on T-10. ISTTOK is equipped with a gallium jet injector and the technical feasibility of gallium jets interacting with plasmas has been investigated in pulsed and ac operation. The first Joint Experiments have clearly demonstrated that small tokamaks are suitable for broad international cooperation to conduct dedicated joint research programmes. Other activities within the IAEA Coordinated Research Project on Joint Research Using Small Tokamaks are also overviewed.

Nonperturbing gas diagnostics of ion beams

The usability of the gas scintillation method in almost nonperturbing diagnostics of ion beams was investigated. The width of the beam was measured on the ITEP-TWAC setup by its image in argon atmosphere at different gas pressures and beam intensities. The dependences of the luminescence intensity of argon atoms on the number of ions in a pulse and the gas pressure in the diagnostic chamber were obtained.

In-line ion detector

An in-line particle detector (IPD) uses secondary electrons for the detection of multiply charged ions with low to medium energy (10-10 keV). The ion detector does not physically intercept the ion beam line and is fully transparent to ions without applied voltages. The activation of the detector is performed by applying appropriate voltages to electrodes, which avoids any physical movement. Equipped with a channel electron multiplier, single particle counting is possible as well as measurement of currents. This detector therefore has a large dynamical range from about 10(-17) to 10(-3) A. The basic principle also allows for ion beam diagnostics.

Highly charged ion beam diagnostics at the mVINIS Ion Source

In order to determine position, dimensions and intensities of multiply charged ion beams at the mVINIS Ion Source, a novel method was developed based on a fluorescent screen and a commercial digital TV camera. The spatial characteristics of multiply charged ion beams (for example the ionization states of Ar2+ to Ar10+) have been precisely measured and analyzed at the TESLA Accelerator Installation for the first time. In this work, we discuss in details the characteristics of Ar8+ion beams. The obtained ion beam characteristics were compared with the results of previously applied conventional methods of ion beam diagnostics.

Design, development, and testing of non-intercepting profile diagnostics for intense heavy ion beams using a capacitive pickup and beam induced gas fluorescence monitors

An intense and focused heavy ion beam is a suitable tool to generate high energy density in matter. To compare results with simulations it is essential to know beam parameters as intensity, longitudinal, and transversal profile at the focal plane. Since the beam's energy deposition will melt and evaporate even tungsten, non-intercepting diagnostics are required. Therefore a capacitive pickup with high resolution in both time and space was designed, built and tested at the high temperature experimental area at GSI. Additionally a beam induced fluorescence monitor was investigated for the synchrotron's (SIS-18) energy-regime (60–750 AMeV) and successfully tested in a beam-transfer-line.

Application of Radiative Electron Capture for the Diagnostics of Spin-Polarized Ion Beams at Storage Rings

It is proposed to apply the radiative electron capture into high-Z projectiles as a probe process for measuring the spin polarization of the hydrogenlike ions at storage rings. We argue that such polarization measurements are possible since the linear polarization of emitted x-ray photons is greatly sensitive to the spin states of incoming ions with nuclear spin I > 1/2. In particular, for K-shell electron capture into the hydrogenlike ions, the linear polarization of light as measured out of the reaction plane is found to be proportional to the degree of ion polarization. Detailed computations for the dependence of the photon polarization on the ion spin states and projectile energies are carried out for the electron recombination into hydrogenlike Bi 82+ ions.

Preliminary Research Results for the Generation and Diagnostics of High Power Ion Beams on FLASH II Accelerator

The preliminary experimental results of the generation and diagnostics of high-power ion beams of FLASH II accelerator are reported. The high-power ion beams presently are being produced in a pinched diode. The method for enhancing the ratio of ion to electron current is to increase the electron residing time by pinching the electron flow. Furthermore, electron beam pinching can be combined with electron reflexing to achieve ion beams with even higher efficiency and intensity. The anode plasma is generated by anode foil bombarded with electron and anode foil surface flashover. In recent experiments on FLASH II accelerator, ion beams have been produced with a current of 160 kA and an energy of 500 keV corresponding to an ion beam peak power of about 80 GW. The ion number and current of high power ion beams were determined by monitoring delayed radioactivity from nuclear reactions induced in a 12C target by the proton beams. The prompt γ-rays and diode bremsstrahlung x-rays were measured with a PIN semi-conductor detector and a plastic scintillator detector. The current density distribution of ion beam were measured with a biased ion collector array. The ion beams were also recorded with a CR-39 detector.

Particle beam and X-ray imaging with thin CsI scintillating plates

At the Laboratori Nazionali del Sud (LNS), Catania, Italy, in the framework of digital radiography and ion beam diagnostics, the use of thin monocrystal scintillating plates made from CsI(Tl) has allowed us to obtain promising results in terms of high sensitivity, compactness, and handiness. In both techniques, a charge-coupled device camera is used to observe the light produced in the crystal when it is crossed by X-rays, in case of radiography, or by charged particles, in case of beam imaging. Spatial resolution has been measured with X-rays as a function of the plate thickness (100 /spl mu/m to 2 mm), and particular care has been taken in order to perform the imaging of low-intensity radioactive beams (I/sub beam/<10/sup 5/ pps) that will be produced with the EXCYT facility at LNS.

Diffraction radiation from relativistic heavy ions

In recent years, the relativistic heavy ion beams at new accelerator facilities are allowed to obtain some new interesting results (see, for instance, Datz et al., Phys. Rev. Lett. 79 (18) (1997) 3355; Ladyrin et al., Nucl. Instr. and Meth. A 404 (1998) 129). The problem of non-destructive heavy ion beam diagnostics at these accelerators is highly pressing. The authors of the papers (Rule et al., Proceedings of the Seventh Beam Instrumentation Workshop, Argonne IL, AIP Conference Proceedings, Vol. 390, NY, 1997; Castellano, Nucl. Instr. and Meth. A 394 (1997) 275) suggested to use diffraction radiation (DR) appearing when a charge moves close to a conducting surface (Bolotovskii and Voskresenskii, Sov. Phys. Usp. 9 (1966) 73) for non-destructive electron beam diagnostics. The DR characteristics are defined by both Lorentz-factor and the particle charge, and do not depend on its mass. The estimation of feasibility of using DR for relativistic ion beam diagnostics is undoubtedly interesting.

A self-calibrating ion beam profiler based on a CsI scintillator

We report on the test results obtained with a prototype beam profiler based on a thin slit and a CsI scintillator, read out by means of a compact photomultiplier. Such a device has proven to be suitable to perform ion beam diagnostics at low and very low intensities. In particular, our device is suitable for being used in the energy and intensity ranges expected at the EXCYT radioactive ion beam facility, that is currently under development at LNS Catania.

Design aspects and status of construction of the mVINIS ion source

The mVINIS ion source is a multiply charged heavy ion source based on the electron cyclotron resonance effect. This machine is a part of the Tesla Accelerator Installation, an ion accelerator facility whose construction has been going on at the VINČA Institute of Nuclear Sciences in Belgrade, Yugoslavia. mVINIS is an advanced version of the Dubna electron cyclotron resonance ion source 14-2, constructed at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. It is a complete injector, consisting of an ECR ion source, focusing and steering elements, an analyzing magnet, a vacuum system, and an ion beam diagnostic system. The main parts of mVINIS have been designed and manufactured at JINR, while the vacuum equipment, power supplies, ion beam diagnostics, and control system were purchased elsewhere. The preliminary testing (magnetic field measurements, vacuum testing, testing of the ECR ion source) has been performed at JINR, and the final assembly of the mVINIS and measurement of the ion beam parameters have been going on at the VINČA Institute.

Developments on the KSU-CRYEBIS, a user facility for low energy, highly charged ions

The KSU-CRYEBIS, a CRYogenic electron beam ion source, supplies experiments with low-energy, highly charged ions of numerous species. The supplied charge states cover the range from 1+ to 52+, with typical beam currents of a nA for low charge states and a few pA for the highest charge states. The ion energies cover the range from 0.3 to 165 keV per charge. This is an unusually broad range of final ion energies and hence requires an unusual dynamic ion transport system. This paper presents advances made with respect to the CRYEBIS ion beam transport, diagnostics, and identification. In addition, an update on the developments of ion beams with very high duty cycles is given.

Ion beam preparation of 7Li + for precision experiments at heavy ion storage rings

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 drastically reduced. After separation of the ground state ions from the triplet states of 7 Li + by the combination of laser and electron cooling, a bunched and cooled ensemble of fast moving high precision clocks with minimized perturbations by space charge effects and intra beam scattering is available.

Use of a charge coupled device-camera system for optical diagnostics of intense ion beams

Among the various possibilities for investigating the properties of ion beams, two of the most important principles for determining the beam quality are profile measurements using wires or slit apertures, and different kinds of emittance measurement devices. However, most of the commonly used systems have the disadvantage of being either destructive to the beam, or at least to have a considerable influence on the further beam propagation downstream of the point of measurement. Also, for the investigation of intense ion beams, thermal problems on the scanners themselves might arise. Observation of particles emitted from the ion beam in radial direction allow an indirect but nondestructive observation of the beam. Of the different optical methods that exist to accomplish this, we recently conducted an investigation on the possibilities to employ a charge coupled device-camera system for such nondestructive beam diagnostics in our space-charge compensation test stand. First, experimental results on optical profile measurements are presented and compared to results obtained by a slit scanner and a wire scanner. Additionally, to gain a better understanding of the measured data, optically obtained sectional profiles behind a slit and a circular aperture were analyzed. Possibilities for gaining information on the two-dimensional beam profile and the beam emittance are explored.

Preparation of relativistic 7 Li + ion beams for precision experiments at storage rings

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 7Li+ 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 drastically reduced. After separation of the ground state ions from the triplet states of 7Li+ by the combination of laser and electron cooling, a bunched and cooled ensemble of fast moving high precision clocks with minimized perturbations by space charge effects and intra beam scattering is available.

CR-39 nuclear track detector application for the diagnostics of low energy high power ion beams

This report presents the investigation results of spectral composition of ion bemas generated by magneto-insulated ion diode of “MAC-M” accelerator. Energetical and mass characteristics of the accelerated ion beam were determined by Thomson spectrometer with CR-39 plate detector. Accelerated ion energy was from 40 up to 240 keV. Mass composition contained hydrohen, nitrohen and carbon ions. The individual track analysis shows the track form, depth and diameter dependence on ion mass and energy.

The potentialities of H − beam diagnostics by laser photodetachment electrons

The previously proposed method of diagnostics for negative ion beams based on electrons produced from single-photon detachment, is considered. The potentialities of such diagnostics by laser probing of a H − beam are theoretically investigated. Analytical expressions for the power density of a photon target, in which two-photon detachment of ions causes the deterioration of the accuracy in nonperturbative measurements of beam parameters, are obtained. The estimation for the H − beam is made at the Moscow Meson Factory Linac.

Intense ion-beam-transport experiments using a z-discharge plasma channel

A z-discharge plasma channel is used to confine and transport an intense proton beam. A pinch-reflex ion diode on the NRL Gamble II accelerator focuses a proton beam onto the entrance aperture of a 2.5 cm diam, 1.2 m long z-discharge transport system. The beam ions are charge and current neutralized in the discharge plasma, and execute betatronlike orbits in the magnetic field of the discharge. Ion beam diagnostics include shadowbox imaging and prompt-γ radiation measurements from LiF targets. Under appropriate conditions, 95% particle transport and 90% energy transport are observed, with the only energy loss attributed to classical stopping in the channel gas. The transverse phase-space distribution of the beam measured by the shadowbox is consistent with full charge and current neutralization of the transported beam.

ICF target diagnostics on PBFA II (invited)

Particle Beam Fusion Accelerator II is a light-ion fusion accelerator that is presently capable of irradiating a 6-mm-diam sphere with ∼50 kJ of 5.5-MeV protons in ∼15 ns. An array of particle and x-ray diagnostics fielded on proton Inertial Confinement Fusion target experiments quantifies the incident particle beam and the subsequent target response. An overview of the ion and target diagnostic setup and capabilities will be given in the context of recent proton beam experiments aimed at studying soft x-ray emission from foam-filled targets and the hydrodynamic response of exploding-pusher targets. Ion beam diagnostics indicate ∼100 kJ of proton beam energy incident within a 1.2-cm radius of the center of the diode with an azimuthal uniformity which varied between 6% and 29%. Foam-filled target temperatures of 35 eV and closure velocities of 4 cm/μs were measured.