Coordinated underground measurements of gamma-ray emitting radionuclides for plasma physics research.

Forty-eight samples made of CaF, LiF and YVO were placed inside the KSTAR Tokamak and irradiated by neutrons and charged particles from eight plasma pulses. The aim was to provide information for plasma diagnostics. Due to the short pulse durations, the activities induced in the samples were low and therefore measurements were performed in five low-background underground laboratories.

First fusion proton measurements in TEXTOR plasmas using activation technique.

MeV particle loss measurements from fusion plasmas, in particular alpha particles, remain difficult in large fusion devices and further R&D is needed for ITER. This paper describes the first attempt to measure 3 MeV escaping fusion protons emitted from TEXTOR tokamak plasmas using activation technique. This technique was successfully demonstrated, initially, in 2006 on the JET tokamak.

New developments in the diagnostics for the fusion products on JET in preparation for ITER (invited).

Notwithstanding the advances of the past decades, significant developments are still needed to satisfactorily diagnose “burning plasmas.” D–T plasmas indeed require a series of additional measurements for the optimization and control of the configuration: the 14 MeV neutrons, the isotopic composition of the main plasma, the helium ash, and the redistribution and losses of the alpha particles. Moreover a burning plasma environment is in general much more hostile for diagnostics than purely deuterium plasmas.

Charged fusion product loss measurements using nuclear activation.

In ITER, α particle loss measurements will be required in order to understand the alpha particle physics. Techniques capable of operating in a fusion reactor environment need further development. Recent experimental studies on JET demonstrated the potential of nuclear activation to measure the flux of escaping MeV ions.

Angular distribution of proton leakage from a fusion plasma using ultra low-level gamma-ray spectrometry.

This experiment aimed at studying a technique to measure the leakage of charged particles from a fusion plasma. The activity induced in samples of various materials placed on a special holder inside a Tokamak was measured using ultra low-level gamma-ray spectrometry (ULGS) performed in three underground laboratories. In total, 27 radionuclides were detected in this experiment.

In-vessel activation monitors in JET: progress in modeling.

Activation studies were performed in JET with new in-vessel activation monitors. Though primarily dedicated to R&D in the challenging issue of lost diagnostics for ITER, which is being addressed at JET with several techniques, these monitors provide for both neutron and charged particle fluences. A set of samples with different orientation with respect to the magnetic field is transported inside the torus by means of a manipulator arm (in contrast with the conventional JET activation system with pneumatic transport system).

A low-level activation technique for monitoring thermonuclear fusion plasma conditions.

Optimisation of the confinement and sustainability of a thermonuclear plasma requires methods to monitor processes in the plasma. In this work three materials were used as activation targets (Ti, MgF2 and a TiVAl compound). They were placed inside the joint European Torus (JET) vacuum chamber.