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VERSION:2.0
PRODID:-//Memento EPFL//
BEGIN:VEVENT
SUMMARY:The role of fast ions in stabilising the ion temperature gradient 
 mode
DTSTART:20170703T103000
DTEND:20170703T113000
DTSTAMP:20260916T212129Z
UID:07ce6f6587d6aa2e25884aafdee9cf9fab8d6c888e7c2fa8ffed27ca
CATEGORIES:Conferences - Seminars
DESCRIPTION:Aylwin Iantchenko\, Chalmers University of Technology\, Gothen
 burg\, Sweden\nThermonuclear fusion is a potential candidate for providing
  a clean source of energy and satisfying the high electricity demands of t
 he future. The fuel in a typical reactor is heated to a very high temperat
 ure forming a gas of charged particles known as a plasma. The plasma has t
 o reach a self-sustainable regime to minimise the input power required to 
 drive the reactor. Reaching this regime demands a sufficiently low transpo
 rt of energy\, which remains one of the biggest challenges in plasma physi
 cs today. Turbulence driven by small scale instabilities causes large heat
  and particle transport and is a major limiting factor of current fusion d
 evices. Above a critical value\, the ion temperature gradient increases th
 e growth of a microinstability - the ion temperature gradient mode- believ
 ed to dominate the ion energy transport.\n\nIt has recently been discovere
 d that energetic ions generated by auxiliary heating may reduce the growth
  of this instability. By applying the gyrokinetic formalism and performing
  linear simulations using the local continuum gyrokinetic code GS2\, we ex
 plore the linear physics of this stabilising effect. In order to isolate i
 mportant effects due to the presence of fast ions\, we make use of the fle
 xibility of GS2 to consider approaches of changing the plasma and magnetic
  geometry parameters independently. We assess the possibility to neglect m
 agnetic geometry changes to simplify the analysis\, by investigating its c
 ontribution to the stabilising effect. For the cases studied we find that 
 the Shafranov shift and safety factor profile might have to be taken into 
 account. For fixed density and temperature a destabilising influence of th
 e fast ion density gradient is found\, while the high temperature gradient
  is stabilising\, both as predicted by analytical models. A large part of 
 the observed stabilisation comes from the fast ion contribution to the pla
 sma beta which is the ratio of the total thermal to magnetic pressure. In 
 addition\, the effect of beta is enhanced because of the large density gra
 dients of the fast ions. We investigate the role of hot ion mass and charg
 e in order to evaluate the stabilisation of different types of hot ions. T
 he charge enhances the destabilising effect of the hot ion density gradien
 t\, while increasing the mass improves stability in general. Finally\, the
  possibility of adjusting the electron and ion profiles to account for the
  presence of fast ions without including them as a kinetic species\, is co
 nsidered.\n\n 
LOCATION:PPB019
STATUS:CONFIRMED
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