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SUMMARY:Ionisation Chemistry in the Inner Disc - Morgan Williams [Imperial
  College London]
DTSTART:20250519T130000Z
DTEND:20250519T140000Z
UID:TALK231361@talks.cam.ac.uk
CONTACT:Samuel Turner
DESCRIPTION:In the inner regions of protoplanetary discs\, ionisation chem
 istry controls the fluid viscosity\, and is thus key to understanding vari
 ous accretion\, outflow and planet formation processes. The ionisation is 
 driven by thermal and non-thermal processes in the gas phase\, as well as 
 by dust-gas interactions that lead to grain charging and ionic and thermio
 nic emission from grain surfaces. The latter dust–gas interactions are m
 oreover a strong function of the grain size distribution. Previous chemica
 l networks\, including these chemical processes\, did not accurately captu
 re this dependence on the grain size distribution. In this talk\, I will e
 xplain how our network – which explicitly includes a distribution of gra
 ins\, at minimal extra computational cost  – shows that chemical abundan
 ces (and thus resistivities) may vary by orders of magnitude for a reasona
 ble set of dust distributions. Furthermore\, I will illustrate how the cha
 rge derived on the surface of the grains is expected to severely hinder co
 llisions between these grains in the inner disc – an important effect to
  be included in solving the Smoluchowski equation\, governing the growth a
 nd fragmentation of grains. Finally\, I will show the progress we have mad
 e towards developing 2D magnetohydrodynamic (MHD) simulations of the inner
  disc\, including: multi-species (gas + dust distribution) hydrodynamics\,
  radiation transport\, our self-consistent chemistry\, MHD resistivities a
 nd charge-dependent fragmentation and coagulation of grains.
LOCATION:MR14 DAMTP and online
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