Student Seminar - May 2020

Eduardo Solis Meza

Mass spectrometry is an essential tool in biological and chemical research fields. This
technique is used to quantify the isotopic composition within a sample. Over the years,
this technique has been under continuous development and further applications have
been found. The Engineering Research Center for Extreme Ultraviolet (EUV) Science
and Technology explored the use of EUV radiation sources as the ionisation tool in

mass spectrometers. This became the creation of a novel technique named Time-of-
Flight EUV Mass Spectrometry (TOF EUV MS).

The special characteristics and further application of an EUV radiation source coupled
to a TOF mass spectrometer are being explored and the first results as a possible
plasma diagnostic tool for temperature measurements in ablation processes is
presented in this work.

Fabio Federeci

In the understanding of the behaviour of plasmas in conditions typical of the divertor target,
great importance has the detachment process and the impact of ELMs on a detached divertor.
In detached conditions ELMs are seen to cause a temporary reattachment of the plasma to the
target, leading to increased heat and particles fluxes. To gain insight on the atomic and
molecular driven processes the Optical Emission Spectroscopy (OES) setup in the linear
plasma device Magnum-PSI was updated to resolve inter-ELM Balmer line emission and used
in conjunction to other diagnostics such as Thomson scattering (TS), fast visible light camera,
infra red camera, pressure gauge (baratron). [1] The ELM-like pulses were performed in a
pure hydrogen plasma for various magnetic field strengths and target chamber pressures. OES
and TS observations were made at a fixed point in space for different axial locations of the
target. [2]
For increasing pressure the influence emission profiles become hollow, an indication the
dominance of molecular processes (molecular activated recombination MAR and ionisation
MAI) over atomic. For deeply detached conditions, obtained by feeding hydrogen in the target
chamber to the point that the plasma is almost extinguished at the target, it is possible to
effectively shield the target from the ELM-like pulse. Analysis is under way to discern what
are the more relevant molecular precursors and their spacial and temporal distribution using
ADAS[3] and Yacora[4], collisional radiative models.