Alpha Diagnostics of Thermonuclear Plasma
Alpha Particle Diagnostics and Data Analysis
Tech Area / Field
- FUS-PLA/Plasma Physics/Fusion
8 Project completed
Senior Project Manager
Novozhilov V V
Russian Academy of Sciences / Physical Technical Institute, Russia, St Petersburg
- VNIIEF, Russia, N. Novgorod reg., Sarov
- Princeton University / Plasma Physics Laboratory, USA, NJ, Princeton
Project summaryAlpha particle behavior in high temperature tokamak plasmas is one of the key issues which will determine conditions for ignition and stationary operation of the fusion reactor. Among a few diagnostics techniques of alpha particles behavior in plasma so called charge-exchange diagnostics is the most informative and provides straightforward interpretation. It is based on the energy analysis of neutral atomic fluxes escaping from magnetically confined plasma. Neutralization of high energy alpha particles in plasma can be reached by different means such for example as helium beam or pellet injection. All these methods are under intensive study on the leading big tokamaks such as JT-60 in JAERI, JET (Culham) and TFTR (Princeton) . The principal element in the realization of the charge-exchange method is multi channel analyzer of high energy helium and hydrogen atoms. It is being developed at PTI to measure energy spectrum and density of these particles under intensive neutron and gamma irradiation of fusion plasma. It covers practically unreachable particles energy range between 100 keV and 4 MeV. Important part of the program is the development of efficient and long serving alpha particles detectors which at the same time will be insensitive to neutrons and gamma quanta radiation.
The important feature of charge exchange diagnostics is that it can be applied for study of any kind of particle acceleration processes in plasma. So on JT-60, JET, TFTR it can be used for measurements of ion cyclotron heated ions. For more adequate experimental data interpretation one needs to develop physical model which will determine a procedure for transformation of the measured energy spectra to the energy distribution function of fast particles in plasma. For this purpose in the Ioffe Institute an analysis of elementary atomic processes resulting to neutralization of alpha particles and protons will be carried out. It will allow to establish relative role of different secondary processes in the neutralization mechanism. A simulation of the alpha particle behavior in fusion reactor plasma based on the experimental results which are supposed to be obtained on tokamaks is planned to be done. It enables to optimize conditions for ignition and burning of fusion plasma.
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