Compression of a photoinjector electron bunch in the negative-mass undulator

The use of the “negative mass” regime provides stabilization of longitudinal size of dense photoinjector electron bunches moving through a long undulator. This allows one to increase significantly the power capabilities of a terahertz source based on coherent spontaneous emission from a short bunch. However, such type of emission is produced if the bunch length is comparable with the radiation wavelength. This work discusses the use of the negative mass regime to provide effective compression of dense bunches down to “terahertz” lengths

Recent progress on a co-harmonic gyrotron

Results from numerical simulations have demonstrated the principle of a co-harmonic gyrotron, operating with a novel cavity. Such a cavity is capable of generating coherent radiation at both the 2nd and 4th harmonics of the electron cyclotron frequency simultaneously, at frequencies of 37.5 GHz and 75 GHz. Further results are presented here, including refinements to the output section of the cavity, as well as on the on-going testing of the cavity and its associated components, which are required to generate the operating modes of interest

Numerical simulation of a 1.37 THz gyro-multiplier

Numerical simulations using Magic 3-D have been conducted on a promising three cavity gyro-multiplier arrangement. Results have predicted output of the 4th harmonic, at a frequency of 1.37 THz, with output powers on the order of 100 W

Numerical investigation of gyro-multiplier schemes

Numerical simulations using the PiC code Magic 3-D have investigated two distinct gyro-multiplier schemes. Subsequent results have predicted the operation of a single cavity device operating at the 2 nd and 4 th harmonics, at frequencies of 37.5 GHz and 75 GHz, respectively. As a result, this device is currently under experimental investigation. Additionally, a sectioned cavity device has shown promising output, delivering 4 th harmonic output at 1.36 THz. Results of both schemes will be presented

A novel co-harmonic gyrotron

A novel interaction cavity has been designed for a gyrotron, realising co-harmonic generation at the 2nd and 4th harmonic resonances of the electron cyclotron frequency. The output aperture of the cavity has been designed to trap the lower harmonic, whilst allowing output of the upper harmonic. Results from recent numerical simulations, performed using MAGIC 3-D, are presented. The intended co-harmonic behaviour is observed, with simultaneous excitation of the 2nd and 4th harmonics. Results are presented of a refinement of the output structure undertaken with CST Microwave Studio, to ensure that only the 4th harmonic signal is emitted

A novel co-harmonic gyrotron

A novel interaction cavity has been designed for a gyrotron, realising co-harmonic generation at the 2nd and 4th harmonic resonances of the electron cyclotron frequency. The output aperture of the cavity has been designed to trap the lower harmonic, whilst allowing output of the upper harmonic. Results from recent numerical simulations, performed using MAGIC 3-D, are presented. The intended co-harmonic behaviour is observed, with simultaneous excitation of the 2nd and 4th harmonics. Results are presented of a refinement of the output structure undertaken with CST Microwave Studio, to ensure that only the 4th harmonic signal is emitted

A co-harmonic gyro-monotron with a novel corrugated interaction cavity

A novel interaction cavity has been designed for a gyro-monotron, allowing co-harmonic generation at the 2nd and 4th harmonic resonances of the cyclotron frequency. The output aperture of the cavity has been designed to trap the lower harmonic, whilst allowing output of the upper harmonic. Results from recent numerical simulations, performed using MAGIC 3-D, are presented. The intended co-harmonic behaviour is observed, with simultaneous excitation of the 2nd and 4th harmonics. Refinement of the output structure is now being undertaken to ensure only the 4th harmonic signal is emitted