Assessment of the SPIDER beam features by diagnostic calorimetry and thermography

The full-size ITER ion source prototype SPIDER has recently started beam operation; goal parameters: 100keV, 60A negative hydrogen-like ions for one hour. The source is presently operated in volume regime and the beam power is consequently limited. In such configuration, the high resolution calorimeter STRIKE, even though uncooled, may be used instead of the SPIDER beam dump without limiting the beam-on time. STRIKE is formed by unidirectional carbon fiber-carbon matrix (CFC) composite tiles which are exposed to the beam while their temperature is recorded by two infra-red cameras. This setup, thanks to the moderate broadening of the temperature profile guaranteed by the anisotropy of CFC, allows for the determination of detailed features of the beam current distribution (spatial resolution is about 2 mm). Furthermore, positively biasing the CFC tiles permits a direct electrical measurement of the negative ion beam current. Besides the total beam current and beam uniformity, which can be retrieved both by calorimetry and electrical measurement, beamlet divergence and deflection can be determined by infra-red thermography. This contribution describes the characterization of the SPIDER negative ion beam as a function of the source and accelerator parameters by means of the diagnostic calorimeter STRIKE in the volume regime.