Abstract: An apparatus for generating and transporting a charged particle beam. The apparatus has a source which generates the charged particle beam at two current levels, and a magnet system for bending the beam. Particles of different energies are bent along different paths, whereby at a specific height within the magnet system the radial displacement from the beam axis is a monotone function of the difference between the energy and the nominal energy. At this height there is provided an energy selection filter having at least one bimetallic element. This element projects into the beam and, thus, intercepts beam particles; it is designed such that its interception distance decreases with increasing beam current. As a result, the energy range of particles passing the filter is broader at the higher current level broader than at the lower current level.

Abstract: A method and an apparatus for irradiating a relatively large area with a charged particle beam. In the method, a pencil-like beam is generated and spread along a fan axis perpendicular to the beam axis. The fan axis is rotated around the beam axis so that finally a circular area is irradiated. The apparatus includes means for generating a pencil-like beam, a lens system for spreading the beam along the fan axis and means to rotate the fan axis around the beam axis. In a preferred embodiment, the beam is spread such that its transverse intensity distribution increases with increasing distance from the beam center so that the area swept by the beam is irradiated with an even intensity.

Abstract: A target assembly for an electron linear accelerator (LINAC), comprising a target for converting electron beams of different energies into x-ray beams. The target has a variable thickness which can be set to a predetermined value by adjustment means. In a preferred embodiment, the target is provided with a chamber defined by two parallel plates and a bellows connecting both plates. The chamber is filled with a liquid medium of a high atomic number, such as mercury. In operation the medium is pumped through the chamber, and cooled down in a heat exchanger.

Abstract: The apparatus contains a target exposed to a beam of accelerated electrons and an electron absorber positioned behind the target. The acceleration energy of the electron accelerator is monitored by monitoring the travelling range of the electrons in the absorber. For this purpose the electron absorber is made up of several insulated absorber portions which are arranged one behind another. Each of these portions is electrically connected to a separate input of a processing system.The monitoring apparatus is especially well suited for application in electron accelerators in medical radiation therapy, such as linear accelerators.