SPIDER (Source for Production of Ions of Deuterium Extracted from Radio frequency) experiment is operating at PRIMA (Padova Research on ITER Megavolt Accelerator) site since June 2018. It is a test bed to study the operation of an ITER-relevant negative ion source. Caesium (Cs) adsorption on the extraction system, in particular on the plasma grid, lowers the surface work function. This increases the probability of negative ions production and the reduction of coextracted electrons, as experimentally observed. The Cs layer in the SPIDER beam source shall be built up in a controlled and repeatable way by injecting Cs vapors by means of three Cs ovens. A SPIDER Cs oven prototype was procured and tested in the CAesium Test Stand (CATS) at PRIMA site validating the design. Following the experimental tests, few improvements were introduced in the final design of the three Cs ovens for the SPIDER source. Then, the ovens were procured and commissioned before the installation in SPIDER. This paper reports the functional tests of the SPIDER Cs ovens and of their embedded diagnostics. These tests were carried out in CATS, with the aim of characterizing the three ovens and of assessing their reproducibility, in order to validate them for use in SPIDER in the planned experimental campaigns with caesium evaporated in the source.
SPIDER Cs Oven functional tests
Barbisan Marco;Rizzieri Roberto;Capobianco Roberto;Rossetto Federico;Rancan Marzio;Armelao Lidia;Taliercio Cesare;Serianni Gianluigi;
2020
Abstract
SPIDER (Source for Production of Ions of Deuterium Extracted from Radio frequency) experiment is operating at PRIMA (Padova Research on ITER Megavolt Accelerator) site since June 2018. It is a test bed to study the operation of an ITER-relevant negative ion source. Caesium (Cs) adsorption on the extraction system, in particular on the plasma grid, lowers the surface work function. This increases the probability of negative ions production and the reduction of coextracted electrons, as experimentally observed. The Cs layer in the SPIDER beam source shall be built up in a controlled and repeatable way by injecting Cs vapors by means of three Cs ovens. A SPIDER Cs oven prototype was procured and tested in the CAesium Test Stand (CATS) at PRIMA site validating the design. Following the experimental tests, few improvements were introduced in the final design of the three Cs ovens for the SPIDER source. Then, the ovens were procured and commissioned before the installation in SPIDER. This paper reports the functional tests of the SPIDER Cs ovens and of their embedded diagnostics. These tests were carried out in CATS, with the aim of characterizing the three ovens and of assessing their reproducibility, in order to validate them for use in SPIDER in the planned experimental campaigns with caesium evaporated in the source.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
