Characterization of impurity confinement on Alcator C-Mod using a multi-pulse laser blow-off system

Journal Article · Tue Mar 15 00:00:00 EDT 2011 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3565448· OSTI ID:22062278

Howard, N T; Greenwald, M; Rice, J E ^[1]

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1. MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)

A new laser blow-off system for use in impurity transport studies on Alcator C-Mod was developed and installed for the 2009 run campaign. Its design included capabilities for multiple impurity injections during a single plasma pulse and remote manipulation of the ablated spot size. The system uses a 0.68 J, Nd:YAG laser operating at up to 10 Hz coupled with the fast beam steering via a 2D piezoelectric mirror mount able to move spot locations in the 100 ms between laser pulses and a remote controllable optical train that allow ablated spot sizes to vary from {approx}0.5 to 7 mm. The ability to ablate a wide range in target Z along with Alcator C-Mod's extensive diagnostic capabilities (soft x-ray, vacuum ultraviolet (VUV), charge exchange spectroscopy, etc.) allows for detailed studies of the impurity transport dependencies and mechanisms. This system has demonstrated the achievement of all its design goals including the ability for non-perturbative operation allowing for insight into underlying impurity transport processes. A detailed overview of the laser blow-off system and initial results of operation are presented. This includes an investigation into the characterization of impurity confinement in the I-mode confinement regime recently investigated on C-Mod.

• OSTI ID: 22062278
• Journal Information: Review of Scientific Instruments, Vol. 82, Issue 3; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ALCATOR DEVICE
CHARGE EXCHANGE
FAR ULTRAVIOLET RADIATION
INJECTION
MIRRORS
NEODYMIUM LASERS
NEUTRAL-PARTICLE TRANSPORT
PHOTON BEAMS
PIEZOELECTRICITY
PLASMA CONFINEMENT
PLASMA DIAGNOSTICS
PLASMA IMPURITIES
PULSES
SOFT X RADIATION
SPECTROSCOPY