Spider beam source ready for operation

In ITER, each Heating Neutral Beam injector (HNB) will deliver about 16.5 MW heating power by accelerating a negative ion beam up to the energy of 1 MeV for a duration of 1 hour. To this purpose, a large RF-driven plasma source is required to generate a 40A D- or 46A H- ion current, with low electron/ion ratio (<1) and high uniformity over the extraction area (800 mm x 1600 mm). SPIDER experiment is meant to demonstrate the performance of a full scale prototype ion source, complying with the challenging requirements of the ITER HNBs. The SPIDER Beam Source (BS) was delivered to the Neutral Beam Test Facility (NBTF) site in Padova (Italy) in October 2017 by the European Domestic Agency, after about five years procurement phase. A huge effort was devoted during the procurement for quality controls and testing of the BS at the supplier's workshop. However several activities were carried out on NBTF site for verification of interfaces, solution of still open issues, as well as final tests before installation inside the Vacuum Vessel. The NBTF Team undertook the BS site acceptance tests including: pressure and leak tests of the hydraulic circuits; electrical tests; measurement of magnetic field profiles; functionality tests of diagnostics installed on the beam source; checks of grids alignment by means of laser tracker. Accurate positioning of the BS inside the vacuum vessel was performed on-site and various service lines were connected in a very limited space. Several improvements were undertaken in order to guarantee reliability and reduce the risks during the first commissioning and experimental campaign in 2018. After installation, the integrated commissioning phase was initiated, powering the RF and high voltage circuits. This phase will be followed by the first operation in vacuum with negative ion production and low voltage extraction and acceleration.