Alcator C-Mod Weekly Highlights June 11, 2012 FY2012 weeks of research operations Target: 18 Completed: 6.78 Plasma Shots: 1150 Operations ---------- Plasma operations continued at Alcator C-Mod last week. Three run days were scheduled and completed. A total of 71 plasma discharges were produced with a reliability of 82%. The runs were devoted to cold pulse propagation experiments using laser blow-off impurity injection, diagnostic development, and current profile measurements using MSE in plasmas with strong lower hybrid current drive. Operational Details ------------------- On Tuesday and Thursday mornings, MP702, "cold pulse modulation experiments for the study of non-local heat transport and correlation with rotation reversals", was run. The purpose of this experiment is to better characterize heat transport, and its correlation with rotation reversals. Previous experiments have successfully demonstrated the non-local effect of heat transport in the Linear Ohmic Confinement (LOC) regime by CaF2 injection using the laser blow-off system. Issues with magnet power supplies, diagnostics, and the data system impacted this work on both Tuesday and Thursday. However, by Thursday, approximately 1/3 of the run plan was executed and non-local effects over a range of plasma conditions were observed. This work comprises part of the PhD thesis research of an MIT graduate student. MP676 and MP677 were run on Tuesday afternoon. Both of these micro-proposals are part of the polarimeter diagnostic development plan. During most of the run, plasmas previously shown to be compatible with efficient lower hybrid current drive were produced and noise levels on the polarimeter signals and their reproducibility were assessed. During the latter part of the run, plasma current ramps at constant density were programmed, and the response measured on the three polarimeter chords. Analysis of these data is ongoing. On Wednesday, MP704, "observation of current density profile changes in LH discharges with the polarimeter system", was successfully run. The purpose of this work is to develop confidence in using the polarimeter data to help constrain EFIT and improve measurements of the plasma current profile. Changes in the polarimeter signals were measured during lower hybrid pulses of over 800 kW, lasting for 500 ms. The timing of the pulses was varied, and plasma current and electron density scans were made. This work comprises part of the PhD thesis research of an MIT graduate student. On Friday afternoon, following debugging of an issue with a TF power supply converter, MP705, "current profile measurements in plasmas with strong Lower Hybrid current drive", was begun. These experiments continued previous work toward validating LH models using C-Mod plasmas, this time with an improved Motional Stark Effect (MSE) and Diagnostic Neutral Beam (DNB). The current density profile was measured as LH power was increased and as the LHCD phase was changed. This work comprises part of the PhD thesis research of an MIT graduate student. ICRF Systems ------------ The phase control issue with the field-aligned antenna has been traced down and fixed. Tests during Friday's run demonstrated proper operation. Lower Hybrid System ------------------- The LH system was used for runs on Wednesday and Friday this week. Power levels over 800 kW for 700 ms were achieved. Progress on the 4th LH cart continues. The HV bus was installed inside cart 4. Panel interlocks were also installed in cart 4. Testing of a new 4.6 GHz fast ferrite tuner (FFT) prototype up to 120 kW for 20 ms was completed. The FFT prototype exhibited no arcing at this power level and pulse length. Remote Participation, Travel, and Visitors ------------------------------------------ Miklos Porkolab, Martin Greenwald and Dennis Whyte attended and participated in the American Security Project (ASP) event: Magnetic Fusion Energy-Steps to Commercialization (Washington, DC, June 5 at the ASP Headquarters). Dennis gave a presentation entitled: "Smaller & Sooner: How a new generation of superconductors can accelerate fusion's development". The viewgraphs can be found at: http://americansecurityproject.org/resources/fusion/Fusion%20Even%205%20June/Smaller_sooner_ASP.pdf The following day, June 6th, Miklos had an informal luncheon meeting with Ed Synakowski, Stewart Prager and Tony Taylor to discuss the potential impact of FY 2013 Presidential and Congressional fusion funding scenarios. Joshua Stillerman attended a data archiving workshop in Cadarache France as an invited expert. The agenda included presentations from both data consumers who use such systems, and technical groups that provide them. Stillerman presented a talk about MDSplus and the Alcator C-Mod data archive. While there, Josh also attended the kick off meeting for the data archiving prototype design effort being led by GA and the HDF5 group (http://www.hdfgroup.org/HDF5/ _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly