Passive protections against breakdowns between accelerating grids in SPIDER experiment

The European contribution to the development of the ITER NB injector

“…The design of the SPIDER components and the simulation of its physical and electrical behaviors have been accomplished by using several computer simulations [17] and has required development of some dedicated codes [18]. Presently the SPIDER design has been almost completed, with only some details related to the diagnostics and to the tools for assembling are still to be fully defined.…”

Analysis of breakdown on thermal and electrical measurements for SPIDER accelerating grids

“…In another work [5] a model for the evaluation of breakdown effects on power conductors, the design and optimization of passive protections strategy has been described. Such model is constituted by four main power conductors and includes the propagation effects subdividing the transmission line in twelve cells.…”

“…The Acceleration Grids Power Supply AGPS model is unchanged from the previous model described in [5]. Instead the Extraction Grid Power Supply EGPS and the High Voltage Deck HVD model were taken and scaled from the model of the full scale NBI, reported in [6].…”

“…So we fixed the TL model in 2 cells, each 15 m long. For analogous computationally reasons, the distributed core snubber described in [5] has been disregarded here; however this absence is precautionary, as it helps to reduce the transient electrical stress on the system. The bushing and the in-vessel connections have been modeled by a single cell, 1.5 m long, with the same TL structure and values.…”

The Transmission Line for the SPIDER experiment

“…The connection between the Ion Source and its power supplies is realized by means of the Transmission Line (TL), whose inner conductor has to be large enough to accommodate a high voltage conductor, high current busbars, four lines for radio frequency and a number of cables for measurements and for light electric loads. The inner conductor supports also the coaxial magnetic cores and blocking inductors forming the so-called Core Snubbers (CS) [5]. At the Ion Source vessel side, the TL is connected to an electric air-to-vacuum bushing, which allows the connection of all the cables and wires to the relevant beam source components.…”