Tuneable FEM system as a plasma source for biological applications
There is increasing interest in the use of microwave power for industrial applications. A pulsed tuneable microwave source is beneficial as it allows the high electromagnetic field of a high power to be applied to a target without excessive heating. The free electron maser (FEM) is the tuneable source with ability to operate across a wide range of frequencies from 8 to 20 GHz. Using higher frequencies than the common 2.45 magnetron, increases the fields obtained and also beneficial scaling effects on some applications, such as microwave induced plasmas. The paper presents the basic principles of the FEM system as well as the applications of UV.
Low cost undulator magnets for industrial free electron masers
At the University of Liverpool we are developing free electron masers <100 kV as a power source for industrial microwave applications. In order to be considered practical, such a device needs to have a cost comparable with conventional sources of microwave power. To achieve this we required an undulator magnet design which was considerably less expensive than the designs normally used in research-based free electron lasers and free electron masers. This paper describes techniques used to successfully construct low cost undulator magnets.
Two-dimensional gravitational anomalies, Schwinger terms and dispersion relations
Abstract We are dealing with two-dimensional gravitational anomalies, specifically with the Einstein anomaly and the Weyl anomaly, and we show that they are fully determined by dispersion relations independent of any renormalization procedure (or ultraviolet regularization). The origin of the anomalies is the existence of a superconvergence sum rule for the imaginary part of the relevant formfactor. In the zero mass limit the imaginary part of the formfactor approaches a δ-function singularity at zero momentum squared, exhibiting in this way the infrared feature of the gravitational anomalies. We find an equivalence between the dispersive approach and the dimensional regularization procedure. The Schwinger terms appearing in the equal time commutators of the energy momentum tensors can be calculated by the same dispersive method. Although all computations are performed in two dimensions the method is expected to work in higher dimensions too.