Upgrade of reflectometry is ongoing on Experimental Advanced Superconducting Tokamak (EAST) for more comprehensive measurement of plasma density profile and fluctuation. To satisfy requirements of upgraded reflectometry, a new Data Acquisition and Control System(DACS) has been developed.
The profile reflectometry works in 30-110GHz (X-mode) and 40-90GHz(O-mode) with 5 receivers. Each receiver outputs in-phase and quadrature signals simultaneously, so 10 signals need be acquired. Considering beat frequency of 4-10MHz, sampling rate is set as 60 MSPS, and total data rate is 1.2 GB/S. The PXIe-based DACS includes two 8-channel 14-bit 250MSPS digitizers. Data from digitizers is stored in a disk array (RAID 0) with data throughput capacity of 3.6 GB/S. Meanwhile, selected data is transported to a FPGA based real-time computing module, which utilize a pre-trained neural network to invert raw data to plasma density profile. A dedicated 5-channel 250MSPS arbiter waveform generator (AWG) is developed to control voltage control oscillators for frequency sweep. A timing module receive the trigger and clock signal from central controller and synchronize all the digitizers and AWG.
The fluctuation reflectometry operates on 16 fixed frequency points in 50-110GHz (X-mode) and 20-60GHz (O-mode). Receiving antennas are placed on two different poloidal positions to do corelation measurement. Totally, there are 64 signals to be acquired. 8 8-channel 14-bit 60MSPS digitizers are added. The sample rate is 4 MSPS and total data rate is 512 MB/S.
Now the new reflectometry is being installed on EAST, and Its performance will be tested in experimental campaign of 2018.