An a. c. operated mass spectrograph of the Mattauch type.
A mass spectrograph for chemical analysis of solid samples has been developed. The Mattauch arrangement of a 31° 50′ electric deflection followed by a 90° deflection in a magnetic field was used in order to obtain a large mass range in focus on one plate. The accelerating and deflecting voltages, and the current for the electromagnet were obtained from stabilized rectifier circuits connected to the 60‐cycle a.c. supply. The electromagnet with 100 milliamperes gave a field of 18,800 gauss across a ⅛″ gap. During the introduction of the plate or insertion of new electrodes a gate valve was closed to isolate the spectrograph from the pumping system. In this way different samples could be examined rapidly. The ion source was energized by a compact Tesla transformer wound on Lucite cylinders. One exposure covered a mass range from any mass M to a mass 10M.
Surface Studies with the Vacuum Microbalance: Instrumentation and Low-Temperature Applications
Publisher Summary Many metals—for example, in high vacuum or in controlled atmospheres at high or low temperatures show unique surface properties, which can be advantageously extrapolated to more moderate conditions of temperature and pressure. This chapter discusses the advances in the application of vacuum microgravimetry to the study of surfaces of solids. Application of microgravimetry to the measurement of physical properties is traditional. Any physical or chemical variation in a system attended by a change in the mechanical moment associated with a given phase or component is susceptible to precise microgravimetric measurement. The measurement of liquid surface tension by the DeNouy method, magnetic susceptibilities by the Gouy balance, of vapor pressures, and of gas densities by buoyancy balances, and microanalysis, are a few examples of the many classical uses of applied precision microgravimetry. In future advances of surface chemistry, precision vacuum microgravimetry can play a significant part by contributing in understanding of surface phenomena.
The parallel waveform relaxation stochastic Runge–Kutta method for stochastic differential equations
For large-scale non-autonomous Stratonovich stochastic differential equations, we study a very general parallel waveform relaxation process which is on the basis of stochastic Runge–Kutta (SRK) method of mean-square order 1.0 in this literature. The convergence of the whole parallel numerical iterative scheme can be guaranteed and the scheme provides better properties in terms of decreasing the load of the computation and operating speed. At the same time, the related limit method is also introduced as the continuous approximation derived from the iterative scheme. In the approximation interval, it is worth noting that the mean-square order of the parallel numerical iterative scheme can be kept consistent with the previous SRK method at any arbitrary time point, not just at discrete points. Some numerical simulations are presented to elaborate the computing efficiency of the parallel numerical iterative scheme.