Low-loss electron beam transport in a high-power, electrostatic free-electron maser

At the FOM Institute for Plasma Physics \u27\u27Rijnhuizen\u27\u27, The Netherlands, the commissioning of a high-power, electrostatic free-electron maser is in progress. The design target is the generation of 1 MW microwave power in the frequency range 130-260 GHz. The foreseen application of this kind of device is as a power source for electron cyclotron applications on magnetically confined plasmas. The device is driven by a high-power electron beam. For long-pulse operation a low loss current is essential. A 3-A electron beam has been accelerated to energies ranging from 1.35 to 1.7 MeV and transported through the undulator at current losses below 0.02%. Further, it was shown that the beam line accepts an electron energy variation of 5% with fixed beam optics. This is essential for rapid tuning of the microwave frequency, over 10%. Electron beam simulations have shown to be remarkably accurate both for the prediction of the lens settings and for the intercepted current. The operational settings of the beam line which give the highest current transmission are within a few percent of the simulated values

A low-energy-spread rf accelerator for a far-infrared free electron laser

A high electron current and a small energy spread are essential for the operation of a free electron laser (FEL). In this paper we discuss the design and performance of the accelerator for FELIX, the free electron laser for infrared experiments. The system consists of a thermionic gun, a prebuncher, a buncher and two standard commercial linac sections. The gun is operated with a pulse duration of 280 ps and a bunch charge of 200 pC. After compression to 35 ps by the prebuncher, the bunches are accelerated to 4 MeV in the buncher and simultaneously compressed to 6 ps. The principle of the method is that the order of the electrons is conserved in the buncher, so that the resulting more or less linear energy-phase relationship along each bunch can be compensated effectively against space charge forces and the accelerating field gradient in the linacs, via an appropriate choice of the phase of the rf wave. Behind the linacs an rms energy spread of 0.30% has been measured

Prospects for SPICA II

A description is given of the experiment SPICA II, a toroidal screw pinch with non-circular cross section. On the basis of model calculations and experience with past screw-pinch experiments the expected performance of this machine is discussed. A survey is given of the planned diagnostics

Prospects for SPICA II

A description is given of the experiment SPICA II, a toroidal screw pinch with non-circular cross section. On the basis of model calculations and experience with past screw-pinch experiments the expected performance of this machine is discussed. A survey is given of the planned diagnostics