2019 Volume 14 Pages 2405014
As for traveling wave direct energy converter (TWDEC), which was expected to be used for energy recovery of fast protons in D-3He fusion, a new modulation scheme was proposed for better bunching. An analytical formula was derived for complete bunching as an ideal waveform, and use of dual-frequency was proposed for practical application. In the scheme, independent two modulation electrodes were used and applied voltages were obtained by Fourier components of the fundamental and the second harmonic frequencies of the ideal waveform with taking running time between electrodes into account. The effect was confirmed by numerical orbit calculation, and improvement of bunching was found even for the ion beam with energy spread. The effect was indirectly confirmed experimentally by comparing variation of the third harmonic signal with an equivalent value in the orbit calculation. The optimum amplitude of the second harmonic frequency was discussed by comparing the composed waveform with the ideal one.
