Production of a highly charged uranium ion beam with RIKEN superconducting electron cyclotron resonance ion source

A highly charged uranium (U) ion beam is produced from the RIKEN superconducting electron cyclotron resonance ion source using 18 and 28 GHz microwaves. The sputtering method is used to produce this U ion beam. The beam intensity is strongly dependent on the rod position and sputtering voltage. We observe that the emittance of U(35+) for 28 GHz microwaves is almost the same as that for 18 GHz microwaves. It seems that the beam intensity of U ions produced using 28 GHz microwaves is higher than that produced using 18 GHz microwaves at the same Radio Frequency (RF) power.     

Test bench to commission a third ion source beam line and a newly designed extraction system

The HIT (Heidelberg Ion Beam Therapy Center) is the first hospital-based treatment facility in Europe where patients can be irradiated with protons and carbon ions. Since the commissioning starting in 2006 two 14.5 GHz electron cyclotron resonance ion sources are routinely used to produce a variety of ion beams from protons up to oxygen. In the future a helium beam for regular patient treatment is requested, therefore a third ion source (Supernanogan source from PANTECHNIK S.A.) will be integrated. This third ECR source with a newly designed extraction system and a spectrometer line is installed at a test bench at HIT to commission and validate this section. Measurements with different extraction system setups will be presented to show the improvement of beam quality for helium, proton, and carbon beams. An outlook to the possible integration scheme of the new ion source into the production facility will be discussed.     

A long pulse width and high extraction rate arc plasma electron beam source

Based on the principle of vacuum arc discharge under magnetic field, a novel plasma cathode electron- beam source was designed. This device can be used to regulate electron-beam current so as to improve the extrication efficiency of electron beam through regulating the exciting current and thus controlling the density of the plasma electron beam source. Experiment results showed that the arc current change with the magnetic field, to be specific, the stronger the magnetic field was, the smaller the arc current will be, then the density of plasma that penetrated the anode hole to serve as electron beam will be higher. From this experiment, it can be seen that under the condition of 10^?3 Pa air pressure, 100 V arc voltage, 30 A exciting current, we can obtain the electron beam of 40 ms pulse width, and 828 mA current in the extraction rate of 6.1%.     

Losses in a pulsed electron beam during its formation and extraction from the diode chamber of an accelerator

The results of experimental studies of the current and charge balance in the diode unit of the ?ЭpU-500 high-current pulsed electron accelerator (an accelerating voltage of 350–500 keV, a half-height pulse duration of 60 ns, and a total kinetic electron energy of 250 J/pulse) during generation of an electron beam are presented. Planar diodes with multipointed cathodes having diameters of 43–60 mm and manufactured from graphite, copper, and carbon felt were studied. It is shown that the electron-beam divergence in the anode-cathode gap caused by a distortion in the electric field at the periphery of the cathode is the main source of parasitic losses in planar diodes. The half-angle of divergence is 68° at small anode-cathode gaps and decreases to 60° with an increase in the gap. When the diode impedance is matched to the generator’s output impedance (at a gap of 10–12 mm), the charge loss is within 12%.     

Generation of an ion beam in a glow-discharge source

A mechanism of ion extraction from a glow-discharge ion source based on a hollow cathode and used for elemental analysis of solids, is considered Experiments have shown that two oppositely directed ion flows are formed from ions produced in the region of negative glow-discharge fluorescence. One flow has an ion energy ≥ 100 eV, is directed to the cathode, and bombards and sputters the analyzed sample. The sputtered atoms diffuse into the negative-glow region and are ionized. The second flow (low-energy ions) is extracted from the same negative-glow region and transported from the cathode to the surface of the anode chamber owing to an ambipolar diffusion. These ions are extracted from a hole in the anode chamber of a standard ion source by an electric field and are used for mass-spectrum analysis. The energy-distribution width for these ions is ∼5 eV. The intensity of the ion beam extracted from the anode hole is an order of magnitude higher than the intensity of the ion beam extracted from the cathode region. Original Russian Text ? G.G. Sikharulidze, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 2, pp. 105–109.     

Triboemission of charged particles and resistivity of solids

The relation between the triboemission intensity of negatively and positively charged particles and the resistivity of solids was investigated for various solids including metals, ceramics and polymers. It has been found that the triboemission intensity increases steeply and the ratios of the charge intensity of the negatively to positively charged particles decreases gradually with an increase of the resistivity of the solids. These results show that the resistivity of solids governs the triboelectromagnetic phenomena and that the emission mechanism and the characteristics shift from those of conductors through semi-conductors to insulators with the increase of the resistivity of solids. This revised version was published online in August 2006 with corrections to the Cover Date.     

H- beam extraction from a cesium seeded field effect transistor based radio frequency negative hydrogen ion source

H(-) beam was successfully extracted from a cesium seeded ion source operated using a field effect transistor inverter power supply as a radio frequency (RF) wave source. High density hydrogen plasma more than 10(19) m(-3) was obtained using an external type antenna with RF frequency of lower than 0.5 MHz. The source was isolated by an isolation transformer and H(-) ion beam was extracted from a single aperture. Acceleration current and extraction current increased with the increase of extraction voltage. Addition of a small amount of cesium vapor into the source enhanced the currents.     

Progress in the MITICA beam source design

In the framework of the development of the ITER neutral beam (NB) system, a test facility is planned to be built in Padova. A full size prototype of the ITER heating NB injector (MITICA) shall be built and tested at full beam power (17 MW) as per ITER requirements. The design of the MITICA beam source has further progressed following updated optimization and overall integration criteria. In the paper, the major design choices and revisions are presented, together with some results of numerical analyses carried out in order to assess the electrostatic and thermo-mechanical behaviour of the source.     

Ion source with longitudinal ionization of a molecular beam by an electron beam in a magnetic field

A high-efficiency ion source for a mass-spectrometer’s detector of molecular beams and their scattering products is described. The ion source is designed according to a scheme of impact ionization of a beam particle by a longitudinal electron beam in a magnetic field with a strength of up to 130 mT. The design of the source developed is very flexible and has no limitations for use in any experiments with molecular beams. An ionization efficiency of particles of an atomic helium beam of 10^?3 ions/atom has been achieved. The useful signal-to-background ratio in the detector’s chamber is 3 × 10⁴ during detection of ions with mass-to-charge ratio m/q = 4 amu.     

Translocation of charged particles through a thin micropore under pressure-driven flow

Journal of Mechanical Science and Technology - We report the effects of a particle surface charge during translocation through a thin micropore based on the simulation and experiments. The...     

Time-of-flight scintillation spectrometer of charged particles with a subnanosecond time resolution

A time-of-flight spectrometer based on a fast plastic scintillator was developed to study the spectral and angular distribution of charged particles emitted from laser-produced plasmas. The measured time resolution of the spectrometer was ～0.3 ns, which made it possible to observe the fine structure in the spectrum of protons originated from the back surface of the target in experiments on the SOKOL-P laser facility.     

Determining the energy spectrum of a charged particle beam using Cherenkov radiation in the deceleration system

A technique for monitoring the energy and the spectrum width of an electron beam in industrial and medical accelerators using Cherenkov radiation in the deceleration system is described. A mathematical model is constructed, and the spectra and the structure of the radiation field in the microwave region are calculated. In mathematical simulation, particular emphasis was placed on the physical aspects playing an important role in practical application of the proposed technique. A layout of the experimental setup and a procedure for reconstructing the energy spectrum are proposed.     

Effects of electrode geometry on the ion beam extraction of closed drift type anode layer linear ion source

Closed drift type anode layer linear ion source was investigated with focusing on the electrode geometry effects on ion beam emission and anode layer formation. In the electrode geometry, the discharge gap between anode and cathode plays an important role to control anode layer formation as well as electron generation. When the discharge gap is increased from 2 to 3 mm, the ion current density was enhanced from 0.9 to 1.35 mA∕cm(2). Computational simulation by using an object oriented particle in cell showed that the discharge volume was extended due to enhanced electron generation and the electric field at the anode layer was enhanced from 1.32 to 1.52 MV∕cm.     

Ten-microsecond pulsed molecular beam source and a fast ionization detector

We describe a pulsed gas valve which we have developed for use as a molecular beam source. In order to observe the performance of the pulsed beam source, we also have developed an ionization detector with a rise time of about 1 micros. The pulsed valve produces very intense supersonic molecular beam pulses of about 10 micros duration for light gases such as H2 and He, and of somewhat longer duration for heavier gases. As a new tool for the study of molecular collisions, the pulsed beam technique offers substantial advantages over the conventional continuous-beam method for experiments which are limited by the signal-to background ratio for scattered products.     

Emission of submicron aerosol particles in operating a laser beam printer

Laser beam printers can be substantial sources of submicron particles in the indoor environment. The present work investigated particle emissions from a commercial laser beam printer (LBP), which was one of single component, non-magnetic, non-contact mode type LBPs, in various operating conditions. Size distribution and number concentration of particles were measured by a scanning mobility particle sizer (SMPS). The size distribution of particles generated from the printer was 20–200 nm in equivalent mobility diameter, regardless of the operating condition. When the fuser system was operated by fuser controller without development and the temperature of the heating roller was 190°C, particles were detected and their peak concentration was about 10³ particles/cm³. Zero percent coverage white papers and five percent coverage black papers, were used, the peak concentrations were 1.5×10⁵ particles/cm³ and 3.3×10⁵ particles/cm³, respectively. These results suggest that the sources of submicron particle generation were rubber of heating roller, paper, and toner.     

Shot-to-shot reproducibility in the emission of fast highly charged metal ions from a laser ion source

The generation of fast highly charged metal ions with the use of the sub-nanosecond Prague Asterix Laser System, operated at a fundamental wavelength of 1315 nm, is reported. Particular attention is paid to shot-to-shot reproducibility in the ion emission. Au and Pd targets were exposed to intensities up to 5 × 10(16) W∕cm(2). Above the laser intensity threshold of ～3 × 10(14) W∕cm(2) the plasma is generated in a form of irregular bursts. The maximum energy of protons constituting the leading edge of the fastest burst reaches a value up to 1 MeV. The fast ions in the following bursts have energy gradually decreasing with the increasing burst number, namely, from a value of about 0.5 MeV∕charge regardless of the atomic number and mass of the ionized species.     

A large-area continuous accelerator with the extraction of a high-density electron beam

The design features of the electron accelerator with a large-area 200-keV beam and results of its investigation are described. The accelerator is based on a set of discrete longitudinal filament cathodes and operates in the continuous mode. The cross section of the beam extracted into the atmosphere is 40 × 50 cm², and the maximal current density of the extracted electron beam is up to 100 μA/cm². The nonuniformity of the current density distribution over the electron beam cross section is 10% or less.     

Measuring the distortion in nuclear emulsion using α particles from a radioactive source

A technique for measuring the distortion in nuclear emulsions using α particles from a ²³²Th(²¹²Po) radioactive source is described. The distortion measured in a 15-μm-thick emulsion layer of a single-sided FoMos film is presented.     

Characterization of plasma ion source utilizing anode spot with positively biased electrode for stable and high-current ion beam extraction

The operating conditions of a rf plasma ion source utilizing a positively biased electrode have been investigated to develop a stably operating, high-current ion source. Ion beam characteristics such as currents and energies are measured and compared with bias currents by varying the bias voltages on the electrode immersed in the ambient rf plasma. Current-voltage curves of the bias electrode and photographs confirm that a small and dense plasma, so-called anode spot, is formed near an extraction aperture and plays a key role to enhance the performance of the plasma ion source. The ion beam currents from the anode spot are observed to be maximized at the optimum bias voltage near the knee of the characteristic current-voltage curve of the anode spot. Increased potential barrier to obstruct beam extraction is the reason for the reduction of the ion beam current in spite of the increased bias current indicating the density of the anode spot. The optimum bias voltage is measured to be lower at higher operating pressure, which is favorable for stable operation without severe sputtering damage on the electrode. The ion beam current can be further enhanced by increasing the power for the ambient plasma without increasing the bias voltage. In the same manner, noble gases with higher atomic number as a feedstock gas are preferable for extracting higher beam current more stably. Therefore, performance of the plasma ion source with a positively biased electrode can be enhanced by controlling the operating conditions of the anode spot in various manners.     

烃源岩氯仿沥青的加速溶剂萃取和传统萃取方法的对比

对于加速溶剂萃取方法(ASE)与索氏抽提、超声波萃取、微波萃取、振荡萃取等传统提取方法在烃源岩样品中可溶有机质的萃取效果方面进行了实验对比研究.实验结果表明,ASE对于烃源岩可溶有机质的萃取效果与传统萃取方法有较好的可比性.与传统方法相比,ASE测定烃源岩氯仿沥青“A”的重现性更好,所得氯仿沥青“A”值的相对标准偏差(n=10)为2.6％;对于饱和烃和芳香烃组分的回收率优于其它方法,有利于对于饱和烃与芳烃的后续分子地球化学分析测试.此外,ASE自动化程度高,操作简单,萃取时间短,消耗溶剂少,是一种便捷和环保的萃取方式.