Patent GB-844774-A (GB)
Title: Improvements relating to electrical computing apparatus
Inventor: HAINE MICHAEL EDWARD
IPC: G06G7/48
Filed: 1957-03-29
Abstract: 844,774. Electric analogue computors. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. June 30, 1958 [March 29, 1957], No. 10384/57. Class 37. Apparatus for determining the distances travelled by a small charged particle in successive intervals of time in a general three-dimensional electrostatic field or in a magnetic field having rotational symmetry comprises, a resistance system points in which represent positions in a chosen co-ordinate system, and means for feeding to appropriate points of the system potentials or currents representative of the local conditions present in the physical system under investigation. so that the components of acceleration of a charged particle may be obtained from the resulting distribution of potential over the system, together with computing apparatus adapted for connection to sets of tapping points said apparatus comprising a unit for each component of movement, each unit comprising means for relating acceleration, velocity and time to distance moved, and the units being so arranged that if the distance moved along one of the axes, taken as a reference axid, has been predetermined,. the corresponding distances moved along the other axis or axes in the same time can be determined. The principles of the resistor network annalogue for field problems are described with reference to Figs. (1-3) not shown, and the injection of currents at the nodes to represent space charges is also dealt with. The potentials across a single mesh, Fig. 4, of the network which gives the particle acceleration in accordance with the field components Xx, X y , X 2  and equations Where e and m are the charge and mass of the particle respectively, are applied to potentiometers R 2 , R<SP>1</SP> 2 , Fig. 5, in series with resistors R 1, R<SP>1</SP>1 of the same value, and potentials corresponding to X, and Y the particle injection velocity are set up from sources shown on potentiometers R3, R 13. Time increments are injected by positioning the ganged wipers on R2, R4, R<SP>1</SP>2, R<SP>1</SP>4 and the output from R4 gives the incremental distances travelled by solving the equations When the time t setting is adjusted to a point where #X corresponds to a mesh length, #Y, the distance travelled in the Y direction, may be read off. The final velocities of the particle in the mesh is obtained from the equations x 2  = #x 1  + #x#t and #y 2  = #y 1  + #y#t by short circuiting the resistors R1, R<SP>1</SP>1, and equal voltages are set up on the wipers of potentiometers S, S1 for switching in place of R3, R 13 to serve as the potentials representing the injection velocities into the next mesh. The introduction of proportionately constants is also discussed. The process is repeated to plot the trajectory and successive values of J Y are added to determine when to shift the probe in the Y direction. A multiplier for insertion in the output to the plotter comprises a pair of reistors R12, R13, Fig. 6 and a source of potential e shunted by a potentiometer R11. When the potentiometer R11 is adjusted to give a zero reading on a galvanometer G, V1/VO is equal to R 12  + R 1  3  Resistor R13 is adjustable to presetthe multiplying factor. An automatic electronic multiplier responsive to the out-of-balance current through G is also described. A modification using tappings off the mid-points of resistors of the mesh; in lieu of the nodes is also described with refernece to Fig. 7 (not shown), and a Kelvin-Varley potentiometer in which the resistance of one adjustable potentiometer is movably connected across pairs of a chain of resistors to enhance accuracy is described with reference to Fig. 8 (not shown). Application of the invention to three dimensions by the construction of three 'dimensional networks and in the case of an electron in a rotationally symmetrical magnetic field produced by current in coils concentric with the axis of symmetry to the solution of equations based on the polar coordinates of the electron #r = -(e/mc)<SP>2</SP> A #  #A # /##,  are also referred to. In this case the network resistors are a function of the radial co-ordinate # and from each nodial point an extra resistance proportional to #, the radial distance from the axis is connected to earth. Currents are fed in at points corresponding to those occupied by coils in the system being investigated, and cores and shrouds are represented by open circuiting the network along lines corresponding to the boundaries of the iron. A multiplier, Fig. 9, for providing the voltage A αA/αZ has a voltage proportional to αA/αZ applied to the wiper of a potentiometer R19 fed from a source E1, and a voltage proportioned to A. applied across the resistor R20. The wipers are ganged and when adjusted to produce a null reading in galvanometer G result in an output A αA/αZ from the wiper on resistor R20.