Effect of limiter biasing on runaway electrons in tokamaks

Journal of X-Ray Science and Technology

et al. 2014

Hard x-ray emission from the Runaway electrons is an important issue in tokamaks. Suggesting methods to reduce the Runaway electrons and therefore the emitted hard x-ray is important for tokamak plasma operation. In this manuscript, we have investigated the effects of external fields on hard x-ray intensity and Magneto-Hydro-Dynamic (MHD) activity. In other words, we have presented the effects of positive biased limiter and Resonant Helical Field (RHF) on the MHD fluctuations and hard x-ray emission from the Runaway electrons. MHD activity and hard x-ray intensity were analyzed using Wavelet transform in the presence of external fields and without them. The results show that the MHD activity and therefore the hard x-ray intensity can be controlled by the external electric and magnetic fields.

Section: Resultsmentioning

confidence: 59%

“…Suppression of Runaway electrons can be explained by three factors [14]. Firstly, Runaway electron is generated by toroidal electric field with minimum amount of:…”

Section: Resultsmentioning

confidence: 99%

x-ray irradiation analysis based on wavelet transform in tokamak plasma

Ghanbari

Journal of X-Ray Science and Technology

et al. 2014

“…Thus avoidance, suppression and termination of Runaway electrons should be developed in present tokamaks in order to realize a reasonable first wall thickness in tokamak fusion reactor [7,13]. Runaway electrons colliding with residual plasma particles and the first wall are two sources for hard x-ray radiations in tokamak [14,15]. Although the intensity of radiations due to collision with heavy nuclei of the first wall is higher, however in both cases dominate mechanism is bremsstrahlung [16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Energetic electrons, hard x-ray emission and MHD activity studies in the IR-T1 tokamak

Agah

Journal of X-Ray Science and Technology: Clinical Applications

2015

Determinations of plasma parameters as well as the Magnetohydrodynamics (MHD) activity, energetic electrons energy and energy confinement time are essential for future fusion reactors experiments and optimized operation. Also some of the plasma information can be deduced from these parameters, such as plasma equilibrium, stability, and MHD instabilities. In this contribution we investigated the relation between energetic electrons, hard x-ray emission and MHD activity in the IR-T1 Tokamak. For this purpose we used the magnetic diagnostics and a hard x-ray spectroscopy in IR-T1 tokamak. A hard x-ray emission is produced by collision of the runaway electrons with the plasma particles or limiters. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons.

“…Therefore, a precise determination of the plasma column shift during confinement is essential to transport it to a control system based on feedback. Over the years, different methods have been developed to analyze the toroidal plasma equilibrium problems (Ghoranneviss and Salar Elahi 2010;Rahimi Rad et al 2010;Salar Elahi and Ghoranneviss 2010c;Ghanbari et al 2011aGhanbari et al , 2011bGhanbari et al , 2012Salar Elahi 2011;Goodarzi et al 2013;Mikaili Agah et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Application of multipole moments and magnetic techniques for determination of tokamak plasma shift

2013

J. Plasma Phys.

In this contribution, we presented approaches for the determination of tokamak plasma column shift based on multipole moments and magnetic techniques. First, we presented analytical details for using this technique. Then, the principle of different models based on this technique for the design and fabrication of six coils will be presented: four modified Rogowski coils (two cosine coils and two sine coils) and two saddle coils (saddle sine coil and saddle cosine coil). Also, to compare the results, the flux loops technique is used. Because of continuous measurements of magnetic field distribution around the tokamak plasma using multipole coils, this technique gives us more reliable information about the plasma current displacement. Moreover, we deduced the plasma current and plasma boundary centers shift using the two semi-empirical techniques in the IR-T1 tokamak. First, the plasma current center is calculated from the vertical field coil characteristics. The calculation is made focusing on the vertical field coil current and voltage changes due to a horizontal displacement of the plasma column. Also, the plasma boundary center shift was measured from the external magnetic coils. The results from these two techniques are compared and discussed.