Tokamak Diagnostics by Fusion Products
Development of Methods and Creation of the Equipment Complex for Thermonuclear Plasma Diagnostics at Tokamak by Neutrons and Charged Fusion Products.
Tech Area / Field
- INS-DET/Detection Devices/Instrumentation
3 Approved without Funding
Kurchatov Research Center, Russia, Moscow
- VNIIEF, Russia, N. Novgorod reg., Sarov
- Massachusetts Institute of Technology (MIT) / Department of Physics, USA, MA, Boston\nJoint European Torus (JET) / Joint Undertaking, UK, Abingdon\nUniversity of California / Department of Physics, USA, CA, Irvine
Project summaryThis version of the Progect differs from the initial proposal due to absence the following works: a) creation of neutron detector of special configuration ("sandwich-radiometer") and its use in T-15 Tokamak, b) creation of escscaping charged fusion products diagnostic for T-15 Tokamak, c) development of new method to measure plasma current profile based on probe alpha particles. Accordingly the overall cost of the Project was reduced from 700k$ to approximately 300k$.
On the other hand in the context of this Project supplementary works will be performed which were absent in the initial proposal. In particular it is intended to study in detail the threshold properties of Bubble Chamber (ВС) and to develop a method to control threshold for further application of ВС not only in tokamaks but in large pulse machines also which will work with DT plasma.
The main goal of the Project is the working out the methods of fusion plasma diagnostics based on the bubble chamber (ВС) use as a threshold detector for energy resolved measurements of DD and DT neutrons, for the measurement of so called "Neutron Knock-On Tails", as well as for the neutron imaging at inertial and magnetic fusion facilities.
The necessity to carry out the work suggested is dictated by latter-day needs for investigation of "alpha-particle problem", the key problem in fusion researches.
Technical approach consists of the use of over-heated liquid for neutron detection. This medium possesses high efficiency to fast neutrons, controlled and sharp threshold to neutron energy, low sensitivity to gammas.
Expected results of the activity on the Project are development and practical tests of new diagnostic methods based on threshold ВС for neutron measurements in large machines with magnetic and inertial plasma confinement.
Bubble Chamber as a neutron threshold detector is used in Controlled Fusion Programme at pulse machines from the beginning of 80th when first images of neutron source region have been obtained . At present such kind detector is considered as the most perspective to measure high energy neutrons at presence of intensive gamma radiation and neutrons with energies below 15 MeV. Firstly ВС was suggested for use in tokamak in Ref. [3-5]. The principal aspects of ВС application to measure neutron "tails" in large fusion machines have been analysed in detail in Ref.  prepared in collaboration with foreign partner - Dr. R.K.Fisher, General Atomic, USA.
In the process of the execution of the Project the following works will be performed:
1. Development of ВС with accurate adjusted threshold for neutron imaging of pulse fusion sources, for spectral measurements of DT neutron peak (measurement of temperature) and for the spectrometry of Knock-On neutrons (measurement of plasma density). The development of the equipment to control ВС operation (precise and the stable assignment of detection threshold, synchronisation of the ВС operation with object studied). The equipment development for neutron image system and for measurement of neutrons flux with the energy above the adjusted threshold.
2. Development of rapid cycling ВС with precise controlled threshold for the measurements of DD and DT neutron peaks and Knock-On neutron tails (confined alpha particles diagnostics) for use as a staff detector in large tokamaks and stellarators. The development of the equipment for control of cyclic ВС operation.
3. The examination of the characteristics of diagnostic methods to be developed for Inertial Fusion machines.
4. The examination of the characteristics of diagnostic methods and equipment to be developed for large fusion machines with magnetic plasma confinement.
5. Working out recommendations for application of the methods to be developed and instrumentation to be created in perspective joint experiments on Fusion Program at large facilities including ITER Project as well as at Inertial Fusion machines. Conceptual design of neutron Knock-On tails Hiaemostirs for ITFR
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