Experimental Study of Toroidicity-induced Alfven Eigenmode (TAE) Stability at High Q(0). PDF Download

Author: S. H. Batha
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 16

View

Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 17

View

Book Description
Experiments to destabilize the Toroidicity-induced Alfven Eigenmode (TAE) by energetic alpha particles were performed on the Tokamak Fusion Test Reactor using deuterium and tritium fuel. To decrease the alpha particle pressure instability threshold, discharges with an elevated value of q(0)> 1.5 were used. By raising q(0), the radial location of the low toroidal-mode-number TAE gaps moves toward the magnetic axis and into alignment with the region of maximum alpha pressure gradient, thereby (in theory) lowering the value of [beta]{sub {alpha}}(0) required for instability. No TAE activity was observed when the central alpha particle [beta]{sub {alpha}} reached 0.08% in a discharge with fusion power of 2.4 MW. Calculations show that the fusion power is within a factor of 1.5 to 3 of the instability threshold.

Author: N. N. Gorelenkov
Publisher:
ISBN:
Category : Magnetohydrodynamic waves
Languages : en
Pages : 13

View

Book Description

Author: G. Y. Fu
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 22

View

Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 28

View

Book Description
The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable by the circulating and/or trapped?-particles through the wave-particle resonances. Satisfying the resonance condition requires that the?-particle birth speed v{sub?} ≥ v{sub A}/2{vert bar}m-nq{vert bar}, where v{sub A} is the Alfven speed, m is the poloidal model number, and n is the toroidal mode number. To destabilize the TAE modes, the inverse Landau damping associated with the?-particle pressure gradient free energy must overcome the velocity space Landau damping due to both the?-particles and the core electrons and ions. The growth rate was studied analytically with a perturbative formula derived from the quadratic dispersion relation, and numerically with the aid of the NOVA-K code. Stability criteria in terms of the?-particle beta?{sub?},?-particle pressure gradient parameter (?{sub {asterisk}}/?{sub A}) (?{sub {asterisk}} is the?-particle diamagnetic drift frequency), and (v{sub {alpha}}/v{sub A}) parameters will be presented for TFTR, CIT, and ITER tokamaks. The volume averaged {alpha}-particle beta threshold for TAE instability also depends sensitively on the core electron and ion temperature. Typically the volume averaged {alpha}-particle beta threshold is in the order of 10−4. Typical growth rates of the n=1 TAE mode can be in the order of 10−2?{sub A}, where?{sub A}=v{sub A}/qR. Other types of global Alfven waves are stable in D-T tokamaks due to toroidal coupling effects.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 24

View

Book Description

Author: G. Y. Fu
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 22

View

Book Description

Author: C.Z. Cheng
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 52

View

Book Description

Author: C.Z. Cheng
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 36

View

Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 15

View

Book Description
A new method of analyzing the toroidicity-induced Alfven eigenmode (TAE) from kinetic theory is presented. The analysis includes electron parallel dynamics non-perturbatively, an effect which is found to strongly influence the character and damping of the TAE -- contrary to previous theoretical predictions. The normal electron Landau damping of the TAE is found to be higher than previously expected, and may explain recent experimental measurements of the TAE damping coefficient. 11 refs., 1 fig., 1 tab.