Research on the phase adjustment method for dispersion interferometer on HL-2A tokamak

A synchronous demodulation system is proposed and deployed for CO_2 dispersion interferometer on HL-2 A,which aims at high plasma density measurements and real-time feedback control.In order to make sure that the demodulator and the interferometer signal are synchronous in phase,a phase adjustment（PA） method has been developed for the demodulation system.The method takes advantages of the field programmable gate array parallel and pipeline process capabilities to carry out high performance and low latency PA.Some experimental results presented show that the PA method is crucial to the synchronous demodulation system and reliable to follow the fast change of the electron density.The system can measure the lineintegrated density with a high precision of 2.0？×10^（18）m^（-2）.

Research on the real-time signal conditioning method for dispersion interferometer in HL-2M

A new CO2 laser dispersion interferometer has been developed in the HL-2 M tokamak to measure the electron density.In order to meet the needs of high-precision measurement,a data acquisition system with real-time signal conditioning(RSC)method is proposed.It can eliminate part of the impacts of environmental factors,such as mechanical vibration,light path changes,and plasma refraction effect during experiments.In harsh environments,the system can measure the line-integrated density with a high precision of 2×10^18 m^-2 with the RSC method.The system has been tested in a recent HL-2 A experimental campaign,and the results show that the RSC method plays an important role in the plasma electron density measurement.

A precision control method for plasma electron density and Faraday rotation angle measurement on HL-2A

The precision of plasma electron density and Faraday rotation angle measurement is a key indicator for far-infrared laser interferometer/polarimeter plasma diagnosis. To improve the precision, a new multi-channel high signal-to-noise ratio HCOOH interferometer/polarimeter has been developed on the HL-2A tokamak. It has a higher level requirement for phase demodulation precision. This paper introduces an improved real-time fast Fourier transform algorithm based on the field programmable gate array, which significantly improves the precision. We also apply a real-time error monitoring module （REMM） and a stable error inhibiting module （SEIM） for precision control to deal with the weak signal. We test the interferometer/polarimeter system with this improved precision control method in plasma discharge experiments and simulation experiments. The experimental results confirm that the plasma electron density precision is better than 1/3600 fringe and the Faraday rotation angle measurement precision is better than 1/900 fringe, while the temporal resolution is 80 ns. This performance can fully meet the requirements of HL-2A.

Changes and Trends in the Current Relations Between Saudi Arabia and Israel

The relations between Saudi Arabia and Israel have become increasingly public after the Trump administration took office in the US.Particularly,Saudi Arabia either holds inconsistent,ambiguous attitudes or gives short shrift to sensitive issues such as Jerusalem issue and the‘Deal of the Century.’Moreover,Saudi Arabia and Israel have been interacting with each other frequently in a public and official way,which further embodies this change in their relationship.The relationship between Saudi Arabia and Israel has a long history,and it has experienced four development stages:mutual isolation,secret contact,open contact,and intimate contact.The changes in the current Saudi-Israeli relations have realistic interests,open interaction,and practical cooperation.The changes in the Saudi-Israeli relations have taken place under the combined effect of the realistic logic of the common political and security dilemma,the transformation of their respective diplomatic strategies and the complementary economic advantages of both sides,as well as the overall environmental changes in the Middle East,the overall fragmentation of the Arab world,and the ups and downs of the US Middle East policy.Saudi Arabia and Israel have formed an anti-Iranian quasialliance,which has certain actual or potential impacts.In the long run,although the changes in the Saudi-Israeli relations are conducive to bilateral cooperation and development in diverse fields,they bring no advantage to the overall stability of the Arab world,and the contradictions within the Arab world will further deepen,which,for example,is represented by a breakthrough in diplomatic relations between Israel and the UAE,Bahrain,Sudan,and Morocco.Besides,geostrategic competition in the Middle East will become more intense and will not contribute to the Middle East peace process.