Experimental Study on the Constant Deceleration Scheme in Traveling Wave Direct Energy Converter

Abstract

Traveling Wave Direct Energy Converter (TWDEC) was proposed to apply to D-3 He nuclear fusion power generation system, and is studied as an energy source of a spacecraft recently where miniaturization of the device is important. Not only the modulation process, but also the deceleration process are important to treat a trade-off between device size and efficiency. The suitable scheme of the constant deceleration, of which experimental investigation was insufficient, was studied. Based on the theory of the scheme, a decelerator for simulation experiments was assembled and deceleration experiments were performed. The efficiency of the highest record in simulation experiments and a fair agreement with the theory were obtained. The problem was also clarified that the improvement of the modulation process was necessary.

Studies on the Axial Position of the Decelerator in Traveling Wave Direct Energy Converter

“…3. This difference around extracting energy comes from the phenomenon that the insufficient modulation results in the remained component of the incident beam in the experiment, and it was observed in the previous experiments [2]. According to the previ- ous research [5], this phenomenon depends on time and insufficient modulation reduces with the lapse of V mod application time.…”

“…V dec is supplied by an RF source synchronized with V mod via coaxial delay lines which have terminals to connect the electrodes at every π/2 phase positions. The electrode D i and D i+4 (i = 2,3,4,5) are connected, respectively, and voltages of the same amplitude are applied although they have some errors to the ideal values, and the details are presented in the previous paper [2]. The decelerator is designed based on the constant deceleration scheme, the details of which are also presented in Ref.…”

“…The decelerator is designed based on the constant deceleration scheme, the details of which are also presented in Ref. 2. In this study, a new function is introduced that this set of decelerator electrodes is movable in the axial direction.…”

“…The best position for conversion efficiency is considered to be the bunching position at which proton density is the highest. In the previous study, the authors conducted simulation experiments and numerical calculations by setting a decelerator at the bunching position [2]. The highest experimental record of the efficiency was obtained, however, the optimum axial position was not examined.…”

A Study of Miniaturization of Traveling Wave Direct Energy Converter for Loading on a Spacecraft

“…Only the previous paper by the authors treats the scheme experimentally. 8) In the previous paper, a decelerator was designed according to the theory of the constant deceleration scheme. The energy conversion efficiency over 30 % was obtained, which was the highest record in the experiment.…”