arXiv subjects

C. Centioli

Publications and source records attributed to C. Centioli.

5 recordsLinked to original sources

arXiv2021

Latest results on quiescent and post-disruption runaway electron mitigation experiments at Frascati Tokamak Upgrade

Results from the last FTU campaigns on the deuterium large (wrt FTU volume) pellet REs suppression capability, mainly due to the induced burst MHD activity expelling REs seed are presented for discharges with 0.5 MA and 5.3T. Clear indications of avalanche multiplication of REs following single pellet injection on 0.36 MA flat-top discharges is shown together with quantitative indications of dissipative effects in terms of critical electrical field increase due to fan-like instabilities. Analysis of large fan-like instabilities on post-disruption RE beams, that seem to be correlated with low electrical field and background density drops, reveal their strong RE energy suppression capability suggesting a new strategy for RE energy suppression controlling large fan instabilities. We demonstrate how such density drops can be induced using modulated ECRH power on post-disruption beams.

physics.plasm-ph↗

arXiv2018

Real-time data compression for data acquisition systems applied to the ITER Radial Neutron Camera

To achieve the aim of the ITER Radial Neutron Camera Diagnostic, the data acquisition prototype must be compliant with a sustained 2 MHz peak event for each channel with 128 samples of 16 bits per event. The data is acquired and processed using an IPFN FPGA Mezzanine Card (FMC-AD2-1600) with 2 digitizer channels of 12-bit resolution and a sampling rate up to 1.6 GSamples/s mounted in a PCIe evaluation board from Xilinx (KC705) installed in the host PC. The acquired data in the event-based data-path is streamed to the host through the PCIe x8 Direct Memory Access (DMA) with a maximum data throughput per channel is 0.5 GB/s of raw data (event base), 1 GB/s per digitizer and up to 1.6 GB/s in continuous mode. The prototype architecture comprises an host PC with two KC705 modules and four channels, producing up to 2 GB/s in event mode and up to 3.2 GB/s in continuous mode. To reduce the produced data throughput from host to ITER databases, the real-time data compression was evaluated using the LZ4 lossless compression algorithm, which provides compression speed up to 400 MB/s per core. This paper presents the architecture, implementation and test of the parallel real-time data compression system running in multiple isolated cores. The average space saving and the performance results for long term acquisitions up to 30 minutes, using different data block size and different number of CPUs, is also presented.

physics.ins-det↗

arXiv2018

The design and performance of the real time software architecture for the ITER Radial Neutron Camera

The neutron detection system for characterization of emissivity in ITER Tokamak during DD and DT experiments poses serious challenges to the performance of the diagnostic control and data acquisition system (CDAcq). The ongoing design of the ITER Radial Neutron Camera (RNC) diagnostic is composed by 26 lines of sight (LOS) for complete plasma inspection. The CDAcq system aims at meeting the ITER requirements of delivering the measurement of the real-time neutron emissivity profile with time resolution and control cycle time of 10 ms at peak event rate of 2 MEvents/s per LOS. This measurement demands the generation of the neutron spectra for each LOS with neutron/gamma discrimination and pile up rejection. The neutron spectra can be totally processed in the host CPU or it can use the processed data coming from the system FPGA. The number of neutron counts extracted from the spectra is then used to calculate the neutron emissivity profile using an inversion algorithm. Moreover, it is required that the event based raw data acquired is made available to the ITER data network without local data storage for post processing. The data production for the 2 MEvents/s rate can go up to a maximum data throughput of 0.5 GB/s per channel. The evaluation of the use of real-time data compression techniques in RNC is also depicted in another contribution. To meet the demands of the project a CDAcq prototype has been used to design and test a high-performance distributed software architecture taking advantage of multi-core CPU technology capable of coping with the requirements. This submission depicts the design of the real-time architecture, the spectra algorithms (pulse height analysis, neutron/gamma discrimination and pile-up correction) and the inversion algorithm to calculate the emissivity profile. Preliminary tests to evaluate the system performance with synthetic data are presented.

physics.ins-det↗

arXiv2001

Technology Update of a Control System Trough Corba Bus

After more than 10 years of activity, FTU (Frascati Tokamak Upgrade) has to face the problem of taking advantage of the new hardware and software technology saving all the investments yet done. So, for example, the 20 years old Westinghouse PLCs (communicating only through a serial line) have to be leaved in operation while a web-based tool has to be released for plan monitoring purpose. CORBA bus has been demonstrated to be the answer to set up the communication between old and new hardware and software blocks. On FTU the control system is based on Basestar, a Digital/Compaq software suite. We will describe how the real time database of Basestar is now accessed by Java graphic tools, LabView and, in principle, any package accepting external routines. An account will be also done in the data acquisition area where a Camac serial highway driver has been integrated in the new architecture still through the CORBA bus

physics.acc-ph↗

arXiv2001

SAN/AFS: Developments in Storage Data Systems on Frascati Tokamak Upgrade

In the last three years, the architecture of Frascati Tokamak Upgrade (FTU) experimental database has undergone meaningful modifications, data and codes have been moved from mainframe to UNIX platforms and AFS (Andrew File System) has been adopted as distributed file system. Further improvement we have added regards data storage system; the choice of SAN (Storage Area Network) over Fiber Channel, combined with power and flexibility of AFS, has made data management over FTU very reliable. Performance tests have been done, showing better transfer rate than previous system, based on JBOD modules with SCSI connection.

physics.acc-ph↗