Progress on development of SPIDER diagnostics

Abstract

A first characterization of the NIO1 particle beam by means of a diagnostic calorimeter AIP Conference Proceedings 1869, 030028 (2017) Abstract. SPIDER experiment, the full size prototype of the beam source for the ITER heating neutral beam injector, has to demonstrate extraction and acceleration to 100 kV of a large negative ion hydrogen or deuterium beam with coextracted electron fraction e¯ /D¯<1 and beam uniformity within 10%, for up to one hour beam pulses. Main RF source plasma and beam parameters are measured with different complementary techniques to exploit the combination of their specific features. While SPIDER plant systems are being installed, the different diagnostic systems are in the procurement phase. Their final design is described here with a focus on some key solutions and most original and cost effective implementations. Thermocouples used to measure the power load distribution in the source and over the beam dump front surface will be efficiently fixed with proven technique and acquired through commercial and custom electronics. Spectroscopy needs to use well collimated lines of sight and will employ novel design spectrometers with higher efficiency and resolution and filtered detectors with custom built amplifiers. The electrostatic probes will be operated through electronics specifically developed to cope with the challenging environment of the RF source. The instrumented calorimeter STRIKE will use new CFC tiles, still under development. Two linear cameras, one built in house, have been tested as suitable for optical beam tomography. Some diagnostic components are off the shelf, others are custom developed: some of these are being prototyped or are under test before final production and installation, which will be completed before start of SPIDER operation.

Neutron measurements at the ELISE neutral beam test facility and implications for neutron based diagnostics at SPIDER

“…The TRansport of Ion in Matter (TRIM) code 22 has been applied to calculate the p(x) for 27-60 keV incident deuterons with a step of 0.5 keV. The dump density was set to 8.902 g/cm 3 . Φ i,j (0, t) is the incident deuterium flux.…”

“…Here, n i,j (z, t) is the time dependent number of deuterons that get deposited per unit volume at a depth z, and σ(z, t) is the D(d,n) 3 He neutron production cross section (see below).…”

“…In order to well estimate the beam uniformity and divergence, a set of diagnostics including the CNESM (close-contact neutron emission surface mapping) system have been designed. 3 The CNESM system is based on Gas Electron Multiplier (GEM) detectors for neutron detection with the aim to resolve the 2D beam intensity profile in deuterium operations at SPIDER. [4][5][6][7] Here, fusion reactions between beam deuterons and deuterons implanted in the copper beam dump will produce about 10 12 neutrons/s spread over 1 m 2 .…”

“…As IR measurements cannot be used on MIT-ICA due to engineering constraints, the experience gained at SPIDER will be instrumental to make CNESM the reference system for deuterium beam profile measurements on MITICA. 11 In order to aid the detector development, neutron emission from D(d,n) 3 He reactions in the beam target experiment must be investigated first.…”

The PRIMA Test Facility: SPIDER and MITICA test-beds for ITER neutral beam injectors

“…STRIKE will be ready to operate on SPIDER during the first phase of experiments. Other diagnostics that are required at the beginning of SPIDER operation (thermocouples, emission and laser spectroscopy, electrostatic probes, visible and infrared (IR) imaging) are almost ready including vacuum windows and the integration with the data acquisition system, while other ones still need R&D to be completed [28]. Prototypes, like tomography cameras, and full setups from sensor to acquisition system, basic analysis and visualization software codes, like those for thermocouples and IR cameras, are being tested at the NIO1 RF source test facility in operation at Consorzio RFX in Padova [29].…”