Acceleration voltage

About: Acceleration voltage is a research topic. Over the lifetime, 1906 publications have been published within this topic receiving 14945 citations.

Direct Imaging of Lattice Atoms and Topological Defects in Graphene Membranes

Abstract: We present a transmission electron microscopy investigation of graphene membranes, crystalline foils with a thickness of only 1 atom. By using aberration-correction in combination with a monochromator, 1-A resolution is achieved at an acceleration voltage of only 80 kV. The low voltage is crucial for the stability of these membranes. As a result, every individual carbon atom in the field of view is detected and resolved. We observe a highly crystalline lattice along with occasional point defects. The formation and annealing of Stone-Wales defects is observed in situ. Multiple five- and seven-membered rings appear exclusively in combinations that avoid dislocations and disclinations, in contrast to previous observations on highly curved (tube- or fullerene-like) graphene surfaces.

A MHz-repetition-rate hard X-ray free-electron laser driven by a superconducting linear accelerator

Abstract: The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created.

Energy calibration of the 500 kV heavy ion implanter ionas

Abstract: Gamma ray yield functions of (p, αγ) and (p, γ) resonance reactions on semi-thick 19F, 23Na, 24,26Mg and 27Al targets were measured and used to calibrate the accelerating voltage and energy resolution of the new 500 kV heavy ion implanter at Gottingen. The energy spread of the proton beam was found to vary linearly with the accelerating voltage from ΔE(200 keV) = 55 eV fwhm to ΔE(500 keV) = 105 eV; it is made up by a 0.012% high voltage ripple and the Doppler broadening of the resonances due to the thermal motion of the target nuclei. A long term stability of the proton energy of Applications of the accelerator for the remeasurement of some resonance energies and widths and for depth profiling of light implanted ions in metals by the resonance broadening method will be briefly discussed.

MAVEN SupraThermal and Thermal Ion Compostion (STATIC) Instrument

Abstract: The MAVEN SupraThermal And Thermal Ion Compostion (STATIC) instrument is designed to measure the ion composition and distribution function of the cold Martian ionosphere, the heated suprathermal tail of this plasma in the upper ionosphere, and the pickup ions accelerated by solar wind electric fields. STATIC operates over an energy range of 0.1 eV up to 30 keV, with a base time resolution of 4 seconds. The instrument consists of a toroidal “top hat” electrostatic analyzer with a $360^{\circ} \times 90^{\circ}$ field-of-view, combined with a time-of-flight (TOF) velocity analyzer with $22.5^{\circ}$ resolution in the detection plane. The TOF combines a $-15~\mbox{kV}$ acceleration voltage with ultra-thin carbon foils to resolve $\mathrm{H}^{+}$ , $\mathrm{He}^{++}$ , $\mathrm{He}^{+}$ , $\mathrm{O}^{+}$ , $\mathrm{O}_{2}^{+}$ , and $\mathrm{CO}_{2}^{+}$ ions. Secondary electrons from carbon foils are detected by microchannel plate detectors and binned into a variety of data products with varying energy, mass, angle, and time resolution. To prevent detector saturation when measuring cold ram ions at periapsis ( $\sim10^{1 1}~\mbox{eV/cm}^{2}\,\mbox{s}\,\mbox{sr}\,\mbox{eV}$ ), while maintaining adequate sensitivity to resolve tenuous pickup ions at apoapsis ( $\sim10^{3}~\mbox{eV/cm}^{2}\,\mbox{s}\,\mbox{sr}\,\mbox{eV}$ ), the sensor includes both mechanical and electrostatic attenuators that increase the dynamic range by a factor of $10^{3}$ . This paper describes the instrument hardware, including several innovative improvements over previous TOF sensors, the ground calibrations of the sensor, the data products generated by the experiment, and some early measurements during cruise phase to Mars.

Plasma treating method and apparatus therefor

Abstract: This invention relates to a plasma treating method and apparatus therefor. The plasma treating method comprises rendering a gas having a critical potential plasmic under a reduced pressure and changing an acceleration voltage for accelerating ions in the plasma towards a sample interposing the critical potential. The plasma treating apparatus comprises means for rendering a gas having a critical potential plasmic under a reduced pressure and means for changing an acceleration voltage for accelerating ions in the plasma towards a sample interposing the critical potential. According to the present invention, the etching step and the film formation step can be carried out alternately and the plasma treating time can be shortened.