Discussion thread: "LIF Diagnostic in the magnetic nozzle of an ECR thruster"

[romainpch]

Hello everyone!

I’m a PhD student at ONERA. The work on the LIF diagnostic in the magnetic nozzle of an ECR thruster I submitted for the for the young researcher’s poster presentation session has been uploaded.
Feel free to have a look and make comments, I will be pleased to answer any question.

[mariomerinomartinez]

Impressive measurements, Romain.

It is very clear from them that ion detachment occurs inwards (at least after the near plume).
Out of curiosity, with the available measurements of electron temperature, did you try to plot the map of ion Mach number?

Best,

Mario

[romainpch]

Thank you Mario,

I have not plotted the ion Mach number yet because Te has never been measured over such a large area. However it is something that could be envisaged in a near future.

[alfiovinci]

Hi Romain,
congrats for the nice results. I'd be curious to know the magnetic field strength throughout the measurements domain, specially at the exit plane. It may be possible to observe complex fluorescence lineshapes due to the Zeeman effect or Paschen-Back effect depending on the external field intensity. What did you observe? Which is the typical shape of your LIF profiles?
Alfio

[romainpch]

Hello Alfio,

In the source of the thruster (0<z<20mm) the magnetic field strength vary from 900G to 450G. At z=80 it is 80G. We did observe a broadening of the LIF profile due to Zeeman effect in the area near to the thruster backplate (0<z<15), it has been caracterized and taken into account int the data post processing. At the exit plane and throughout the plume, the magnetic field is too weak to induce a significant zeeman effect so LIF profiles have been fitted by both a gaussian and an assymetric gaussian. It's the latter that provides the best fits.

[eahedo]

Romain,

Nice measurements and good you confirm ion inwards detachment.

Big magnets make the expansion to be completed before but make the plume to be more divergent (no good for thrust). Is that right?

[romainpch]

Hello Eduardo,

Thank you.
It is right, but actually we observed better performance (higher thrust) with the big magnet configuration. Even if it makes the plume more divergent it accelerates more the ions. The ion density (not shown in my presentation) is also to be taken into account in such analysis.

[yraitses]

Hi Romain,
This is Yevgeny Raitses from PPPL. Can we continue to go over your poster at zoom? Please send me email and i respond with the time:
[email protected]

[eahedo]

Romain, Ok, I see, you have a higher potential fall with the big magnet. I am not sure I understand why. Thanks, --------------------- Eduardo Ahedo Professor of Aerospace Engineering Universidad Carlos III de Madrid Avenida Universidad 30, Of. 7.3.H04 28911 Leganés, España +34 91 624 8234 El jue, 17 feb 2022 a las 16:06, romainpch ***@***.***>) escribió:

…

Hello Eduardo, Thank you. It is right, but actually we observed better performance (higher thrust) with the big magnet configuration. Even if it makes the plume more divergent it accelerates more the ions. The ion density (not shown in my presentation) is also to be taken into account in such analysis. — Reply to this email directly, view it on GitHub <#13 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AXZBHFU5URKEERAIBDWADF3U3UFIRANCNFSM5N752SBA> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you commented.Message ID: <ep2lab/ExB_workshop_2022_website/repo-discussions/13/comments/2197478@ github.com>