The Welding Institute

Allan Sanderson

Colin N Ribton

Colin Ribton

A plasma source apparatus for generating a beam of charged particles is disclosed. The apparatus comprises: a plasma chamber provided with an inlet for the ingress of gas and an aperture for the extraction of charged particles from the plasma chamber; a radio frequency (RF) plasma generation unit for generating a plasma inside the plasma chamber, the radio frequency plasma generation unit comprising first and second resonant circuits each tuned to resonate at substantially the same resonant frequency, the first resonant circuit comprising a first antenna and a first, RF power source adapted to drive the first resonant circuit at substantially its resonant frequency, and the second resonant circuit comprising a second antenna, whereby in use an RF signal is induced in the second antenna by the first resonant circuit due to resonant coupling, the second resonant circuit being configured to apply the induced RF signal to the plasma chamber to generate a plasma therein; and a particle accelerating unit for extracting charged particles from the plasma and accelerating the charged particles to form a beam, the particle accelerating unit comprising a second power source configured to apply potential between the plasma chamber and an accelerating electrode, the region between the plasma chamber and the accelerating electrode constituting an acceleration column. The second power source is adapted to output a high voltage relative to that output by the first, RF power source.

Plasma source apparatus and methods for generating charged particle beams

A charged particle emitting assembly comprises an emitter member ( ) for emitting charged particles of one polarity. A tubular shield electrode ( ) circumferentially surrounds the emitter member and is held in use at the same polarity as the charged particles. A tubular accelerating electrode ( ) is positioned substantially coaxially with the shield electrode ( ) and is held in use at the opposite polarity to the shield electrode. The arrangement is such that charged particles from the emitter member ( ) initially spread laterally outwardly and then are focused into a beam which passes through the tubular accelerating electrode ( ).

Particle beam emitting assembly

Charged particle generation with a resonant electrical circuit

An electron beam welding system having improved deep penetration weld characteristics in which the electron beam is repeatedly deflected from an undeflected nominal position, as the beam traverses along a weld zone, to build up a heat distribution pattern in the vicinity of the weld zone. The heat distribution pattern is made up of a number of substantially distinct zones of different heat density with a preferred pattern comprising three zones with a space between the first and second zones. The third zone leads the second zone and the space trails the second zone in the direction of traversal of the beam with the maximum heat density occurring in the second zone.

Electron beam welding

A method and apparatus for causing a beam of charged particles (4) to impinge on a surface of a workpiece (1,1A) along an impingement path (2) such as a weld joint line is described. The apparatus comprises an electron beam source (3); a first control assembly (24) for guiding the beam along the joint line (2) and for deflecting the beam at successive positions onto the joint line; and a second control assembly (22) into which the beam (4) is launched for deflecting the beam at selected positions into the first control assembly. In an embodiment, X-rays are generated and detected to monitor the condition of the weld.

Controlling charged particle beams

A charged particle collector assembly, particularly for use with an electron beam gun, is described. The assembly comprises a reflection member onto which electrons impinge in use, the reflection member being adapted substantially to absorb particles of one polarity and substantially to reflect particles of the other polarity. A sensor or collector is positioned to receive particles reflected from the reflection member and to generate a corresponding output signal.

Charged particle collection

A charge particle beam generator is described which comprises an annular arrangement of filaments (6) which, when heated, emit electrons. A microprocessor controller (not shown) causes a voltage to be applied across each filament (6) in succession so as to cause the filament to generate electrons. An annular anode (9) is provided radially inwardly of the filaments (6) to accelerated electrons away from the filaments in the form of a beam towards a joint between a pair of workpieces to be welded.

Charged particle beam generation

An electron beam generator for use in electron beam welding wherein the electron beam passes through at least two electromagnetic beam deflecting systems upstream of the electron lens and which act one after another on the beam to define a fixed nonlinear path for the electron beam from the electron gun towards the welding point on a predetermined welding axis, with the other paths being blocked. The fixed path is such that the portion of the beam leaving the last deflecting system is parallel to the portion of the beam from the gun to the first deflection system, and at least one of the beam deflecting systems is offset with respect to the welding axis. In some arrangements the first and last beam portions are in alignment. The coils of the beam deflecting systems are connected in a circuit for controlling the ratio of currents passing through the coils so that the system as a whole is self-compensating for changes in voltage or beam current.

Electron beam welding generators

This concerns an electron beam generator system in which the supply for at least one auxiliary electrode of the electron gun (for example the filament or biasing electrode) is provided by a high frequency oscillator connected to a transformer or other coupling means, the output of which is applied at the electron beam gun column to a component which is itself connected to the output of the high voltage generator; this dispenses with the superimposition of the auxiliary supply on the HT voltage at a remote high voltage generator and with the corresponding auxiliary supply conductor in the conventional high voltage cable between the high voltage generator and the electron beam gun column.

Growing community of inventors

Cambridgeshire, United Kingdom

Allan Sanderson