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This paper reports a technique for the study of pneumatically-conveyed solids. Two equations have been established experimentally which give the pressure gradient and solid velocity along a pipe when non-adhesive spherical particles (up to 7 mm in diameter) are being conveyed with little or no acceleration by an airstream through the pipe. Straight, smooth and horizontal pipes (up to 7 cm in diameter) are considered. Included in the paper is a section examining the practical application of the equations, and a successful check of the equations is made with some values of the variables outside the range studied in the paper.

The Polytron is a toroidal plasma configuration, using 36 magnetic cusps joined point-to-point. This paper presents observations of the acceleration and containment of the plasma. Measurement of the force on the plasma shows that the initial acceleration is given by a particle equation mi(dvphi /dt)=ZeEphi and occurs in thin sheaths in the ring cusp planes. The concept of a non-magnetic effective inductance is experimentally verified. However rapid, although not complete loss of plasma occurs after 1 mu sec for argon, limiting the electron temperature to 30 eV at an electron density of 1020 m-3. This loss is expected and an energy balance at this time implies that electron thermal conduction causes the principal loss of energy. After this loss, the rest of the plasma drifts to the outer wall of the vacuum vessel after about 3 mu sec.

The instrument was developed for the measurement of the acceleration of the rear axle of a vehicle. It was necessary for the recording to be done remotely in order accurately to phase three records, two of acceleration and one of spring load. A new method of remote recording has been developed for the purpose. The paper describes the design of the instrument, its principle of operation, and also, though briefly, the auxiliary equipment. The undamped natural frequency is 300 similar and the maximum reading is 25 g. Damping is provided by filling the casing with light mineral oil and, although less than critical, is sufficient to eliminate from the records any disturbance due to self-oscillation.

In this paper the phenomena of total reflexion are considered, de novo, from the standpoint of the Principle of Huygens, no use whatever being made of the Fresnel formulae for reflexion and refraction. Huygens' principle enables us to evaluate the disturbance appearing in the second medium when light is incident on the boundary between two media and is totally reflected into the first medium. The disturbance takes the form of a superficial wave moving parallel to the boundary. The existence of such a superficial wave is then shown to involve, as a necessary consequence, an acceleration of the reflected wave with reference to the incident wave, the acceleration being zero at critical incidence and increasing to half an oscillation at grazing incidence. The intensity of the superficial wave is at critical incidence greater for the component having the magnetic vector parallel to the surface, but diminishes more rapidly with increasing incidence than for the component having the electric vector parallel to the surface; the phase-advance reaches its maximum value correspondingly sooner. The phase-angle between the two components is evaluated and found to be an acute angle, in agreement with the classical treatment based on the Fresnel formulae, but in disagreement with the conclusions of Lord Kelvin and Schuster. The source of error in the Kelvin-Schuster treatment is pointed out. Experimental evidence regarding the magnitude of the phase-advance of each component separately is available and is in agreement with the classical theory. Finally, a method is described by which the distribution of intensity, state of polarisation, and direction of flow of energy in the superficial wave may be studied experimentally.

More experimental information about the nature of the binding forces between nuclear constituents is necessary before an advance in fundamental nuclear physics can be achieved. By considering the type of information which would be most useful, the conclusion is reached that it necessary to have available protons of energies of about 1000 MeV. in order to carry out the necessary experiments. It is with a method of obtaining protons of this energy that this paper is concerned. An examination of the possibilities of achieving such high energy protons by the existing methods leads to a pessimistic conclusion, and a new method is suggested. This new method, the synchrotron, is described in principle, and its advantages are outlined, a very important factor being its comparatively low cost. An accelerator of this type is being built at Birmingham University with a grant from the Department of Scientific and Industrial Research, and its design is considered in some detail. The magnet and its excitation form the greatest part of the apparatus in size and cost. Several alternative methods are suggested and discussed for both the magnet design and its method of excitation. An air-cored magnet is considered but rejected because of the very large mechanical forces involved and the precision required in positioning the conductors. As a result an iron-cored magnet has been chosen for construction. The excitation of the magnet is to be achieved by a d.c. motor-generator supplied with a fly-wheel. The requirements of the accelerating system, in which is included a radio frequency which changes by a ratio of about 1: 36 during the acceleration, are quite exacting. The methods by which it is hoped that these requirements will be met are outlined. The problems associated with injection and extraction of the particles receive some attention, and a schematic description of the proposed vacuum chamber is included. When protons of energies greater than 1010 eV. are to be obtained by a synchrotron, the cost of the device becomes overwhelming and some alternative method will have to be suggested. The application of the synchrotron being built at Birmingham to accelerating electrons, is limited to achieving electron energies of about 300- 00 MeV. because of radiation losses.

Using a CV76 magnetron at a wave-length of 10.0 cm. (maximum power 500 kw.; power available for acceleration, 300 kw.), and a 3-stage single cavity, electrons were accelerated to a voltage of 0.85 Mev. The expected figure was approximately 1.1 Mev. The paper describes the R.F. work involved in obtaining the result.

In the ‘polytron’ a series of cusp magnetic fields is superimposed on a toroidal discharge. Stability is improved by favourable field curvature, and containment will be good if the plasma acquires a substantial velocity relative to the cusps. This can be achieved by a Hall acceleration mechanism. In this paper a hydromagnetic analysis is presented in which realistic time variations of electric and magnetic fields are allowed, and plasma self-fields are included. An upper bound is set to the acceleration obtainable from a given cusp system and expressed as a critical electric field Ec. The existence of Ec is confirmed experimentally, and it is possible to reproduce experimental waveforms approximately by inserting appropriate parameters into the equations. The effect of a toroidal magnetic field is also considered and a criterion derived for its maximum permissible value. In designing a fusion device this criterion could be an important consideration.

When working out the theory of high frequency beam stacking in accelerators operating with a constant magnetic field it is important to take into account the perturbations of the beam which has already been stacked caused by later acceleration cycles. The main effect of these perturbations is to increase the energy spread of the beam and to alter its mean energy. This paper presents a general formulation of this problem and a solution is given for certain particular cases.

This paper describes the neutron emission observed during an investigation of the characteristics of fast linear Z-pinches using a low-inductance condenser bank. The neutron production is compared with the results obtained elsewhere and is shown to be different in several respects from that obtained with low-power banks, but is quite similar to that reported in more recent, high-power experiments. It is shown that much of the yield is non-thermonuclear, and a number of existing theories for the production of neutrons by acceleration processes in a plasma are discussed. A process of neutron production in fast linear pinches is suggested, which qualitatively accounts for many recently reported results; the proposed mechanism becomes the well-known Colgate process in discharges where m = 0 instabilities lead to narrow necks in the plasma. Reasons are given to account for the absence of appreciable thermonuclear yields which might be expected from theoretical considerations.

This paper gives a short description of some of the properties of accelerators having a vertically increasing field. A discussion is given of the requirements which must be met for optimum acceleration, as well as questions dealing with the existence of equilibrium orbits, the stability of betatron oscillations and the particle acceleration process in accelerators of this type.

The design of a chronograph which will give a time trace subdivided into units and fractional units requires the association of a rotating system and a vibrating or time-keeping system. It a low-frequency vibrating system be employed, the rotating system, although keeping good average time, may show exaggerated errors in unit subdivisions due to acceleration and deceleration between periods of control. The Paper discusses the association of a high-frequency synchronous alternating-current motor with a high-frequency valve-maintained tuning-fork. It deals with the design of valve-maintained motors and condenser-tuned valve-maintained tuning-forks and gives expressions for the frequency of the maintained system for motors coupled to tuning-forks both without and with tuning condensers.

Attention is drawn to an error in the paper of Champeney and Moon. The simplest interpretation of this experiment and that of Moon et al. is that time dilatation is a consequence of acceleration and not of relative velocity.

The paper describes a simple apparatus by means of which the acceleration of gravity can be easily demonstrated. Distances travelled by a falling body during successive time units can be projected directly on to a screen. The apparatus is essentially an arrangement for projecting light from a falling drop of water, the light being interrupted at a constant frequency by revolving sectors.