Ions Of Different Masses Research Articles

Study of ion dynamic effects at low electron densities on the lines He I 447.1 and 492.2 nm

The effects of ion motion on the Stark profiles of the lines He I 447.15 nm (2 3P-4 3D) and its forbidden component He I 447.0 nm (2 3P-4 3F) has been studied in a plasma jet for electron densities between 0.8 × 10 21 and 4 × 10 21 m -3. The ion velocity was changed by using perturbing ions of different masses. An important smearing of the central part of the line was observed, and there was some evidence of an extra-broadening of the line when the ion velocity increased. A comparison of our results with the recent Model Microfield Method calculations shows an improved agreement in the line profile description relatively to previous calculations. A confirmation of these measurements was given by the study of the ion motion effect on the profile of the line He I 492.19 nm (2 1P-4 1D) and its forbidden component He I 492.03 nm (2 1P-4 1F).

Ion Acceleration in an Expanding Rarefied Plasma with Non-Maxwellian Electrons

Scaling laws are derived for the energy spectrum of accelerated ions of different masses and charges. The results are compared with existing experiments.

Beam Profile Monitor Using Rutherford Backscattering from Thin Wires

A wire scanner driven by a stepping motor was built to measure beam profiles of a low energy ion accelerator by Rutherford back-scattering. This permits use of the system also in the undeflected beam where ions of different mass and energy are present. With this monitor, emittance and luminosity of a beam produced by a radio-frequency ion source were measured.

A Diagnostic Method for Time Resolved Spatial Profile Measurements of Proton and Impurity Density and Temperature

A new diagnostic technique, based on elastic scattering of neutral atoms off the plasma ions, is proposed and analyzed. Space and time resolved measurements of the number densities and temperatures of the various components of the plasma are possible by energy analysis of the scattered neutral atoms. The ability to resolve ions of different masses is limited by ion thermal motion and the energy and angular dependence of the scattering cross sections. In hydrogenic plasmas with impurities, the scattering by the impurities is easily resolvable from the scattering of protons, even when the individual impurity contributions cannot be separately resolved. Detected particle count rates are calculated for a conceputal system for a tokamak plasma (n ~ 1013 cm-3, Ti ~ 300 eV). Time resolution of ~ 10 ms with spatial resolution of a few cm are predicted.

Theoretical approaches to the microphonics

The cochlea microphonics have two components; the first component is very sensitive to lack of oxygen and disappears immediately upon the death of the animal; the second component is the smaller fraction (5–25 %) but persists after the death of the animal, and is anaerobic. This paper gives a simple model which can be applied to the understandings of the later part of the microphonic potential. Both perilymph and endolymph in the inner ear may be electrolyte solutions which will behave like homogeneous liquids. If, however, the dynamical reactions are taken in account, these reactions will be different for ions of different masses. As a result, the motion, say of the positive ions, may differ from that of the negative ions. This means that periodically changing electric charge densities will accompany the sound waves. Theoretical approaches to the microphonics in the cochlea are presented.

Systems Analysis of Accelerator and Storage Ring Systems for Inertial Fusion

A computerized systems model is being developed to help assess the relative merits of the various accelerator systems that appear able to meet the requirements for inertial fusion with high energy heavy ion beams. Assessment involves calculating the total cost and parameters that are critical to technical feasibility. Current results showing cost trends and important technical parameters for rf linac/storage ring systems using ions of different mass, charge state, and kinetic energy are presented.

Spectrometer for Measuring Secondary Electron Yields Induced by Ion Impacts on Thin Film Oxide Surfaces

We have developed a spectrometer for studying secondary-electron yields from ion-to-electron converter dynodes. Ions, formed by surface ionization, are mass-analyzed in a small double-focusing mass spectrometer which is followed by a post-accelerating lens to increase the kinetic energy of the ions to ∼30 keV before they strike an ion-converter dynode. The ion-converter dynode is a flat, narrow strip positioned along the the axis of rotational symmetry of a cylindrical lens and is rotatable about this axis. Secondary electrons are emitted from the thin-film oxide surface of the converter dynode. They are accelerated to ∼30 keV in the cylindrical lens and are focused onto a silicon solid state detector for pulse-height analysis of the secondary-electron spectrum. Idividual secondary-electron groups containing 1,2,3,…, etc., electrons are resolved and recorded in a 400-channel pulse-height analyzer. Deconvolution of the resulting energy spectrum gives precise estimates of secondary electron yields for monatomic or polyatomic ions of different mass, atomic number, energy, and angle of entry. Experimental results are given for thin films of oxidized aluminum, plasma-anodized aluminum, and for an activated beryllium-copper surface. Our results support the hypothesis that the Poisson distribution represents the minimum statistical variance (most sharply peaked distribution) that is physically attainable for secondary electron emission from an ion-converter dynode.

Use of Isotopic Abundance Ratios in Identification of Polychlorinated Biphenyls by Mass Spectrometry

Abstract Polychlorinated biphenyls are industrial compounds which are being detected throughout the global ecosystem. Because of the presence of other residues, combined gas chromatography-mass spectrometry must be used for their confirmation. Using isotopic abundance ratios, the theoretical probability of the occurrence of ions of different masses in the molecular cluster has been calculated for the polychlorinated biphenyls, polychlorinated terphenyls, and chlorinated naphthalenes. Mass spectra of mono-through decachlorobiphenyl have been taken with a unit resolution, computer-controlled GC-MS system and parent ion clusters were matched with the theoretical isotopic patterns. This method provides the unambiguous identification of polychlorinated biphenyls in the presence of other substances.

Zum Lumineszenz-Abklingverhalten von ZnS/Cu

The decay characteristics of ZnS/(10−4) Cu have been investigated by ion pulse excitation. The excitation density could be varied by using ions of different masses.

Method of computing magnet coil current settings for the NRL isochronous cyclotron

In order for the modern isochronous cyclotron to accelerate ions of different mass and charge state to a variable final energy, the magnetic field in the accelerating region must be precisely tailored. A deviation of 15 G in 18 kG may lead to a loss of beam. The approximate magnetic field of the NRL cyclotron for isochronous accelaration is achieved by iron pole pieces arranged in a 3-sector, hill-valley configuration. This basic field may deviate from that necessary for isochronous acceleration by two or more kG at some radii. Compensation for this field error is achieved by various current-carrying coils wound in the magnet gap. This paper discusses the extent of the magnetic field measurements and the computer program developed at NRL for computing operational parameters (knob-settings) for all current- carrying coils. Innovations introduced in the calculations include minimizing the first harmonic introduced by the extraction elements and imperfections of the iron. In addition, allowance is made for the lack of linear independence of the trim coils as well as for the perturbation of the flutter field due to the trim coils. The influence of the extraction elements on the accelerating region and the function of each element for beam extraction is also discussed. Measurements on the internal and external beam verify the calculations.

Die dreidimensionale Stabilisierung von Ladungstr�gern in einem Vierpolfeld

It is shown that particles of a specific chargee/m are confined in three dimensions by a high frequency electric quadrupole field with the potentialϕ=c · U(t)· (x 2+y 2−2z 2). The confinement is mass selective. The theoretical predictions are verified by experiments with ions of different masses and with electrons. The mass selection, maximum number of stored charges and their mean life time in the field are measured. Furthermore the influence of a magnetic field on the motion of the charges is investigated.

The Electron Affinity of Iodine from Space-Charge Effects

The electron affinity of iodine atoms has been determined by a direct method in which only iodine atoms and electrons were involved. The value so obtained is 74.6 k-calories, which is in good agreement with values obtained by other methods. The concentration of the several ions of different masses (I— and E—) have been calculated from their effect on space charge. It has been established that iodine has no effect on the thermionic emission of tungsten.

The Positive Ray Analysis of Water Vapor Ionized by Impact of Slow Electrons

An electromagnetic method of separating gas ions of different mass, such as that used by Dempster, has been employed in a study of the ions produced by electron impact in water vapor. The principal ions appearing were ${({\mathrm{H}}_{2}\mathrm{O})}^{+}$ and ${(\mathrm{OH})}^{+}$. Of these the ${({\mathrm{H}}_{2}\mathrm{O})}^{+}$ ions were more abundant. Unmistakable evidence was obtained that a third type of ion, probably ${({\mathrm{H}}_{3}\mathrm{O})}^{+}$, was produced in very small quantities. ${\mathrm{H}}^{+}$ and ${\mathrm{H}}_{2}^{+}$ ions were always very few in number or unobservable. No ${(\mathrm{OH})}^{\ensuremath{-}}$ or any other negative ions were observed.Ionization potentials for ${({\mathrm{H}}_{2}\mathrm{O})}^{+}$ and ${(\mathrm{OH})}^{+}$.---The ionization potential corresponding to ${({\mathrm{H}}_{2}\mathrm{O})}^{+}$ was 13\ifmmode\pm\else\textpm\fi{}1.5 volts, being probably in agreement with the ordinarily measured ionization potential. The ${(\mathrm{OH})}^{+}$ ionization potential was not distinguishably different, but it was difficult to measure this quantity owing to some overlapping of the ${({\mathrm{H}}_{2}\mathrm{O})}^{+}$ and ${(\mathrm{OH})}^{+}$ peaks.Relative abundance of the ions as a function of pressure.---A study was made of variation in the relative abundance of the ions as a function of pressure. The ${({\mathrm{H}}_{2}\mathrm{O})}^{+}$ ion appears to be the primary ion, as it predominates at low pressures, but is of the same order of magnitude as the ${(\mathrm{OH})}^{+}$ ion at high pressures (0.007 mm).