A heterodyne dispersion interferometer for wide bandwidth density measurements on DIII-D.
Rev Sci Instrum
; 89(10): 10B105, 2018 Oct.
Article
in En
| MEDLINE
| ID: mdl-30399752
ABSTRACT
In order to improve both the density and particularly the temporal resolution beyond previous dispersion interferometers (DIs), a heterodyne technique based on an acousto-optic (AO) cell has been added to the DI. A 40 MHz drive frequency for the AO cell allows density fluctuation measurements into the MHz range. A CO2 laser-based heterodyne DI (HDI) installed on DIII-D has demonstrated that the HDI is capable of tracking the density evolution throughout DIII-D discharges, including disruption events and other rapid transient phenomena. The data also show good agreement with independent density measurements obtained with the existing DIII-D two-color interferometer. The HDI line-integrated density resolution sampled over a 1 s interval is â¼9 × 1017 m-2. Density fluctuations induced by MHD instabilities are also successfully measured by the HDI.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Rev Sci Instrum
Year:
2018
Document type:
Article