TY - JOUR
T1 - Mapping electron dynamics in highly transient EUV photon-induced plasmas
T2 - a novel diagnostic approach using multi-mode microwave cavity resonance spectroscopy
AU - Beckers, J.
AU - van de Wetering, F.M.J.H.
AU - Platier, B.
AU - van Ninhuijs, M.A.W.
AU - Brussaard, G.J.H.
AU - Banine, V.Y.
AU - Luiten, O.J.
PY - 2019/1/16
Y1 - 2019/1/16
N2 - A new diagnostic approach using multi-mode microwave cavity resonance spectroscopy (MCRS) is introduced. This can be used to determine electron dynamics non-invasively in an absolute sense, as a function of time and spatially resolved. Using this approach, we have for the first time fully mapped electron dynamics specifically during the creation and decay of a highly transient pulsed plasma induced by irradiating a background gas with extreme ultraviolet (EUV) photons. In cylindrical geometry, electron densities as low as 1012 m-3 could be detected with a spatial resolution of (sub)100 μm and a temporal resolution of (sub)100 ns. Our experiments clearly show production of electrons even after the in-band EUV irradiation fades out. This phenomenon can be explained by both photoionization by out-of-band EUV radiation emitted by the EUV source later in time and delayed electron impact ionization by electrons initially created by in-band EUV photoionization. From the analysis, the absolute width of the electron cloud in the probing volume could also be retrieved temporally resolved. This data clearly indicates cooling of electrons. From an application perspective, it is demonstrated that the method can be used as a non-invasive and in-line monitor for ionizing radiation in terms of beam power, profile and pointing stability.
AB - A new diagnostic approach using multi-mode microwave cavity resonance spectroscopy (MCRS) is introduced. This can be used to determine electron dynamics non-invasively in an absolute sense, as a function of time and spatially resolved. Using this approach, we have for the first time fully mapped electron dynamics specifically during the creation and decay of a highly transient pulsed plasma induced by irradiating a background gas with extreme ultraviolet (EUV) photons. In cylindrical geometry, electron densities as low as 1012 m-3 could be detected with a spatial resolution of (sub)100 μm and a temporal resolution of (sub)100 ns. Our experiments clearly show production of electrons even after the in-band EUV irradiation fades out. This phenomenon can be explained by both photoionization by out-of-band EUV radiation emitted by the EUV source later in time and delayed electron impact ionization by electrons initially created by in-band EUV photoionization. From the analysis, the absolute width of the electron cloud in the probing volume could also be retrieved temporally resolved. This data clearly indicates cooling of electrons. From an application perspective, it is demonstrated that the method can be used as a non-invasive and in-line monitor for ionizing radiation in terms of beam power, profile and pointing stability.
KW - electron density
KW - EUV induced plasma
KW - MCRS
KW - microwave CAVITY resonance spectroscopy
KW - multi-mode MCRS
KW - photon induced plasma
UR - http://www.scopus.com/inward/record.url?scp=85056718286&partnerID=8YFLogxK
U2 - 10.1088/1361-6463/aaeb17
DO - 10.1088/1361-6463/aaeb17
M3 - Article
AN - SCOPUS:85056718286
VL - 52
JO - Journal of Physics D: Applied Physics
JF - Journal of Physics D: Applied Physics
SN - 0022-3727
IS - 3
M1 - 034004
ER -