PLASMA
SEMINARS AND GROUP MEETINGS
The style of the seminars
will be informal/chaotic/interactive, following the
established tradition. The format of the presentations
can be a tutorial on a topic of interest, a report
on just completed/ongoing/just starting/potentially
interesting research projects, a literature review, a lecture
by a passing visitor or anything else worthwhile that anyone
cares to suggest. The speakers will be interrupted freely
and asked to defend themselves. For background reading,
only the most relevant or the most recent references are
posted; please follow the paper trail from there. The
schedule is subject to change on short notice, but
what you see posted here is always up to date; the seminars
are also announced via the department's seminar server (group
meetings are not). Please email Alex
Schekochihin if you would like to receive email updates
on these seminars. "Plasma group meetings (or journal
clubs)" will discuss current affairs (ongoing projects,
new litearture etc.) as well as
feature some presentations that are even more informal than
seminars. They are open to all members of the Oxford Plasma Theory Group. While
some expected contributions are pre-announced, everything is
TBC and people wishing their work to be discussed can
volunteer contributions without prior notice. Unlike for the
seminars, there will not be full-spam-list email reminders of
the group meetings. The seminars
and group meetings are organised by Michael
Barnes and Alex
Schekochihin, please contact them with any queries or
if you wish to present something.
Past
seminar database: Autumn
2007; Winter-Spring
2008; Summer
2008; Autumn
2008; HT
2009; TT
2009; Summer
2009; MT
2009; HT
2009; TT 2010; Summer 2010; MT 2010; HT 2011; TT 2011; Summer 2011; MT 2011; HT 2012; TT 2012; Summer 2012; MT 2012; HT 2013; TT & Summer 2013; MT 2013; HT 2014; TT & Summer 2014; MT 2014; HT 2015;
TT & Summer 2015; MT 2015; HT 2016; TT & Summer 2016; Autumn/MT 2016; HT 2017; TT & Summer 2017; Autumn/MT 2017; HT 2018; TT & Summer 2018; MT 2018; HT 2019; TT & Summer 2019; MT 2019; HT 2020; TT & Summer 2020; MT 2020; HT 2021;
TT & Summer 2021; Autumn/MT 2021; HT 2021; TT & Summer
2022; Autumn/MT 2022;
HT
2023; TT & Summer 2023;
Autumn/MT 2023;
HT 2024; TT & Summer 2024;
Autumn/Michaelmas Term of 2024
The seminars/group
meetings will be on Tuesday at 14:00 in the
Simpkins Lee Room, Beecroft Building, except where indicated
otherwise below, in red.
It will be possible to join
these meetings (when they are held in SL Room) on ZOOM
--- details available from Alex on request.
Those who join these
meetings on ZOOM are asked keep their video cameras on.
The ZOOM system in
Simpkins Lee Room does not display a list of participants
whose cameras are off. It is not germane to these informal
meetings to have invisible listeners of whom those present
in the room are unaware, so if you are unable or
unwilling to turn on your camera, you cannot join the
meeting.
Here is a list of all Physics
seminars.
If you know exactly what
you are going to do, what is the point of doing
it? Pablo
Picasso I don't give a damn about astrophysics, explain to me what is going on. Anatoly Spitkovsky Have you subtracted
the baby with the bathwater? Steve Balbus I wouldn't say these are theoretical arguments... Let's just call them arguments. Francois Rincon This qualitative explanation is not of sufficient quality. Eugene Churazov If you mean it seriously, this is actually a very good question. Minhyong Kim This paper is a tour de farce. Ian Abel |
It is better to be
vaguely right than exactly wrong. Carveth Read (usually
attributed to Maynard Keynes)
Now that
everyone knows this is the new Pandora's box,
they are all going to jump into it. Francois Rincon This is not
real, it's a Platonic absolute.---The real thing is
more Platonic and more absolute. Alex Schekochihin
& Anthony Field |
[these quotes are mostly from these seminars and the Vienna
meetings]
Wk |
Date |
Time & place |
Speaker &
Topic |
Background
reading |
Visitors in town |
Tue 3 Sept |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Group Meeting (organised by MICHAEL BARNES) Open mic |
Yohei
Kawazura (Utsunomiya U) |
||
Tue 10 Sept |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Group Meeting (organised by ALEX) Juan Ruiz Ruiz & Yujia Zhang will report on the 2024 Varenna-Lausanne Workshop |
R. Nies's new
paper |
||
Tue 17 Sept |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Journal Club (organised by ALEX) 1) Leo Turica will discuss Montani & Moretti "Symmetries of the electromagnetic turbulence in a tokamak edge" 2) Michael Nastac will discuss Lobo & Sayal "Theory of phase-space hydrodynamics of electron and ion holes in collisionless plasmas" 3) Robbie Ewart & Prakriti Palchoudhury will discuss Squire et al. "Rapid, strongly magnetized accretion in the zero-net-vertical-flux shearing box" 4) Prakriti Palchoudhury will discuss Johnston et al. "A unified phenomenology of ion heating in low-beta plasmas: test-particle simulations" |
arXiv:2407.01241 PoP 31, 092301 (2024) arXiv:2409.05467 arXiv:2409.07015 |
||
Surui Li leaves the group to return to Cambridge. | |||||
Tue 24 Sept |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised
by MICHAEL NASTAC) Lynn Wilson (NASA) --- Nonequilibrium electron velocity distribution functions in the solar wind The solar wind is a
supersonic flow of ionised particles, called a plasma,
streaming away from the Sun. These particles are not
observed to be in thermal or thermodynamic
equilibrium. This is because nearly all particle
dynamics are governed by non-collisional processes and
the particles experience long-range forces (i.e.,
Coulomb potentials of nearby, charged particles).
There are multiple particle species in the solar wind
as well, including, but not limited to, electrons,
protons, alpha particles, and multiple charge states
of heavier ions up past uranium. For the particle
species that we can resolve and properly measure, we
observe non-Maxwellian features in the velocity
distribution functions (VDFs). In fact, no species
that is properly resolved is ever observed to be a
single, isotropic Maxwellian or even a bi-Maxwellian
distribution. That is, all VDFs are observed to have
nonthermal tails and/or multiple phase-space density
peaks and/or self-similar profiles. We will focus on
the electron VDFs and their nonequilibrium features
with a special emphasis on the often observed
self-similar VDFs, also known as flattop
distributions. These are especially interesting
because they may be direct evidence of phase-space
compressibility and/or inelastic collisional
processes, both time-irreversible phenomena. Such
nonequilibrium kinetic processes are of fundamental
importance in physics and at the heart of some of the
biggest outstanding questions in kinetic theory.
|
ApJS
236, 41 (2018) +erratum ApJS 269, 62 (2023) ApJS 243, 8 (2019) ApJS 245, 24 (2019) ApJ 893, 22 (2020) Front. Astron. Space Sci. 9. 1063841 (2022) +references therein slides are here |
Lynn
Wilson (NASA) |
|
Plamen Ivanov
leaves Oxford and moves to EPFL. James Edmiston moves to Oxford from Cambridge as DPhil student to work with Dmitri Uzdensky, Michael Fitzgerald & Alex Schekochihin. |
|||||
Mon 30 Sept |
15:45 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised
by ALEX) Pavel Kovtun (U Victoria) --- Dissipation and causality in relativistic MHD |
JCAP
10(2022)039 JHEP 10(2019)034 JHEP 05(2017)001 PRD 95, 096003 (2016) |
Tunde
Fulop (Chalmers) Pavel Kovtun (U Victoria) |
|
Tue 1 Oct |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised
by ALEX) Tunde Fulop (Chalmers) --- Running away and radiating |
CPC
268, 108098 (2021) NF 64, 086033 (2024) (+references therein) |
||
Wed 2 Oct |
11:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised
by ALEX) Pavel Kovtun (U Victoria) --- Effective field theory for hydrodynamic fluctuations |
JHEP
02(2021)200 PRL 128, 071601 (2022) arXiv:1805.09331 J. Phys. A 45, 473001 (2012) |
||
Riju Dutta moves
to Oxford from IISc (Bangalore) as DPhil student to
work with Dan Kennedy & Alex Schekochihin. Agi Wierzchucka returns to Oxford as DPhil student to work with Dmitri Uzdensky and Alex Schekochihin. Robin Greif's postdoc stint at Oxford comes to an end. |
|||||
0 |
Tue 8 Oct |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Group Meeting (organised by PATRICK & TUNDE) We will watch the colloquium organised by the Nobel Committee following the announcement of the 2024 Nobel Prize in Physics |
Tunde
Fulop (Chalmers) |
|
I |
Tue 15 Oct |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Group Meeting (organised by MICHAEL BARNES) Juan Ruiz Ruiz, Robin Greif, Robbie Ewart, and Michael Nastac will report on the APS DPP Meeting |
Tunde
Fulop (Chalmers) |
|
II |
Tue 22 Oct |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Group Meeting (organised by ALEX) Christopher Everett (Oxford Astro) --- 1) Kinetic modelling of astrophysical jets via a discrete momentum method; 2) Spacecraft propulsion a la magnetic reconnection |
1) RAS Tech.
Instr., rzae036 2) AIAA 2023-0448 |
Tunde
Fulop (Chalmers) Dominika Maslarova (Chalmers) |
III |
Tue 29 Oct |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Group Meeting (organised by ALEX) 1) Barry Ginat --- Cosmological turbulence ...followed by Plasma Journal Club 2) Barry Ginat will discuss Imbrogno et al. "Long-living equilibria in kinetic astrophysical plasma turbulence" |
1) preprint from author on request 2) arXiv:2408.02656 |
Peter
Catto (MIT) Tunde Fulop, Ida Ekmark (Chalmers) |
Robbie
Ewart leaves Oxford to take up a postdoctoral
fellowship with SCEECS at
Princeton and Maryland. |
|||||
IV |
Tue 5 Nov |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised by TUNDE) Ida Ekmark (Chalmers) --- Fluid and kinetic modeling of runaway electron seed generation during disruptions Highly energetic
runaway electron (RE) beams can be generated during
tokamak disruptions, and since the RE generation is
exponentially sensitive to initial plasma current,
these beams pose a critical challenge for future
tokamaks. Accurate simulations of tokamak disruptions
are therefore essential for the development of
successful mitigation strategies and safe operation.
However, when simulating such disruptions, fluid
plasma models are often preferred due to their low
numerical cost, even though they generally are less
accurate than kinetic models. We have compared
simulations using both fluid and kinetic modeling of
the RE seed generation for a diverse set of disruption
cases in ITER and SPARC.
|
JPP 90,
905900306 (2024) |
Tunde
Fulop, Ida Ekmark (Chalmers) Per Helander (IPP Greifswald) |
V |
Mon 11 Nov |
12:30 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised
by DMITRI) Nicolas Brughmans (KU Leuven) --- Non-axisymmetric accretion disk instabilities: new possibilities beyond the MRI Accretion disks are
assumed to be turbulent as they are highly unstable to
magnetic instabilities driven by shear flow, with the
celebrated axisymmetric MRI accepted as basic
mechanism. I will start by introducing MHD
spectroscopy, which is a general framework to study
the collection of (un)stable Fourier eigenmodes of MHD
systems. These tools are required for a global
treatment of non-axisymmetric instabilities, where
nearby singularities from the overlapping MHD continua
interact. I will then show how a new type of
ultra-localised, non-axisymmetric instability in thin
disks [1] is obtained. This Super-Alfvenic Rotational
Instability (SARI) leads to unprecedented continuous
2D regions in the complex eigenfrequency plane, with
eigenmodes corotating with the super-Alfvenic flow and
shielded from the artificial boundaries by Alfven
resonances. Finally, I will show recent work of mine
that highlights how non-axisymmetric modes extend
regimes accessible to instability, with growth
comparable to the MRI [2], and how visualising the
global MRI/SARI mode structure in time gives more
insight into their nature. The Legolas code can
be used in that regard to study spectra for a variety
of (non-)ideal MHD equilibria.
|
1) ApJS
259, 65 (2022) 2) ApJ 968, 19 (2024) |
Nicolas
Brughmans (KU Leuven) Tunde Fulop (Chalmers) Per Helander (IPP Greifswald) |
Tue 12 Nov |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised
by ALEX) William Morris (UKAEA) --- Fusion plants and (some of) what they need |
slides
from JPP colloquium PPCF 64, 064002 (2022) |
||
VI |
Tue 19 Nov |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Group Meeting (organised by MICHAEL BARNES) Megan Evans --- Turbulence in a 2D large-aspect-ratio tokamak model with magnetic and flow shear [DPhil transfer presentation] |
report from author on request |
Tunde
Fulop (Chalmers) Chris Hamilton (IAS Princeton) Per Helander (IPP Greifswald) |
VII |
Tue 26 Nov |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Group Meeting (organised by MICHAEL BARNES) Lucas McConnell --- Importance of kinetic effects in the scrape-off-layer using the Moment Kinetics Code [DPhil transfer presentation] |
report from author on request |
Tunde
Fulop (Chalmers) Chris Hamilton (IAS Princeton) J.-B. Fouvry, Sofia Flores, Anwar El Rhirhayi (IAP) |
VIII |
Tue 3 Dec |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised
by TUNDE) Louis Richard (Uppsala) --- Ion and electron heating in symmetric magnetic reconnection jets Magnetic reconnection
is a ubiquitous plasma process powering some of the
most extreme energy sources in the visible Universe.
The reconfiguration of the magnetic field topology
results in converting electromagnetic energy into bulk
flows and accelerating charged particles. The
reconnection outflow, in particular, plays a crucial
role in plasma heating associated with magnetic
reconnection. Using the Earth's magnetotail as a
laboratory, we study how the reconnection outflow
deposits its energy into the surrounding plasma. We
present a comprehensive analysis of the magnetic
reconnection outflows and the associated energy
conversion mechanisms using NASA's Magnetospheric
Multiscale spacecraft. Our study reveals that the
reconnection outflow dissipates its energy through the
generation of turbulence [1]. This turbulent energy
transfer substantially contributes to the magnetic
reconnection energy budget. We show that the
non-adiabatic ion motion in the strongly curved
magnetic fields associated with the reconnection
outflow results in fast scattering and heating of
thermal ions [2]. In contrast, ions with higher
energies get accelerated by the convective electric
field on the scale of the reconnection outflow [3].
Furthermore, our analysis also reveals that electrons
are efficiently heated by a magnetic field-aligned
electric field, which develops to maintain macroscopic
quasi-neutrality [4]. This study illuminates the
intricate interplay of various physical processes
within the reconnection outflow, advancing our
understanding of energy dissipation and particle
energization associated with magnetic reconnection.
|
1) PRL
132, 105201 (2024) 2) PRL 131, 115201 (2023) 3) JGR 127, e2022JA030430 (2022) 4) preprint from author on request |
Tunde
Fulop (Chalmers) Chris Hamilton (IAS Princeton) Anwar El Rhirhayi (IAP) Louis Richard (Uppsala) |
9 |
Tue 10 Dec |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Group Meeting (organised by DAN KENNEDY) Harry Dudding (UKAEA) --- Applying the method of multiple scales to the Maxwell-Vlasov system Plasma physics models
often rely on a priori assumptions about the relative
importance of terms in governing equations. While
these assumptions simplify analysis, they can also
restrict the model's validity. This talk presents an
application of the method of multiple scales (MMS) [1]
to the Maxwell-Vlasov system, constructing a uniformly
valid hierarchy of equations for plasma dynamics.
Unlike conventional approaches, the MMS framework
avoids fixed assumptions about the expansion
parameter's relationship to physical parameters,
introducing independent fast- and slow-scale
coordinates in space and time. The additional degrees
of freedom introduced by the new coordinates enable
the systematic elimination of secular terms, yielding
an explicit Reynolds-like turbulence average. The
resulting equations encompass established regimes such
as kinetic MHD and gyrokinetics. Key insights include
a strongly magnetised electromagnetic analogue of
Landau damping, and novel terms in gyrokinetic-like
equations that account for kinetic MHD effects and
Langmuir waves. Implications for global gyrokinetic
models and their predictive capabilities are also
explored.
|
1) MMS tutorial |
|
10 |
Tue 17 Dec |
No
seminar. Beecroft Building closed for power
testing. |
|||
Tue 24 Dec |
No seminar.
Merry Xmas! |
||||
Tue 31 Dec |
No seminar. Happy NY! | ||||
Tue 7 Jan |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Journal Club (organised by ALEX) 1) Archie Bott will discuss Walsh et al. "Magnetized ICF implosions: non-axial magnetic field topologies" 2) Robin Greif will discuss Ingelsten et al. "Data-driven discovery of a heat flux closure for electrostatic plasma phenomena" |
1) arXiv:2411.10538 2) arXiv:2411.18358 |
||
0 |
Tue 14 Jan |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Journal Club (organised by ALEX) 1) Juan Ruiz will discuss Chen et al. "The effects of zonal fields on energetic-particle excitations of reversed-shear Alfven eigenmode: simulation and theory" 2) Michael Nastac will discuss Vanthieghem & Levinson "Relativistically magnetized collisionless shocks in pair plasma: I. Solitons, chaos, and thermalization" |
1) NF
65, 016018 (2025) 2) arXiv:2411.16484 |
|
I |
Tue 21 Jan |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised
by BARRY) Stephane Colombi (IAP) --- TBA |
Stephane Colombi (IAP) |
|
II |
Tue 28 Jan |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Tutorial (organised by ALEX) Sergei Sharapov (UKAEA) --- Fast ion physics, Part I |
||
III |
Tue 4 Feb |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Tutorial (organised by ALEX) Sergei Sharapov (UKAEA) --- Fast ion physics, Part II |
||
IV |
Tue 11 Feb |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised
by MICHAEL HARDMAN) James Cook (UKAEA) --- TBA/TBC |
||
VIII |
Tue 11 Mar |
14:00 SL Room & ZOOM (ask Alex for link) |
Plasma
Seminar (organised
by ALEX) Uddipan Banik (IAS, Princeton) --- TBA |
Uddipan
Banik (IAS) |