[Casa] CAS Seminar Wednesday Nov 13

[Todd Satogata]

-------- Forwarded Message --------
Subject: 	Reminder: CAS Seminar Wednesday
Date: 	Fri, 8 Nov 2024 08:23:18 -0500
From: 	Geoffrey A. Krafft <krafft at jlab.org>



Hi All,

On Wednesday, November 13 a seminar will be held at ODU's Center for Accelerator
Science at 1:30.

Here is the meeting link for those of you who would like to
attend remotely.

https://odu.zoom.us/j/6804937969?omn=98950214907

There should be no password required. The broadcast will
originate at the CAS conference room for those of you who would
like to meet in person. Those of you in Norfolk, it would be
nice for us to all meet!

Speaker: Zachary Caudell

OPTICAL INVESTIGATION OF A LOW-PRESSURE PLASMA IN A SUPERCONDUCTING
RADIO-FREQUENCY CAVITY

The state-of-the-art cryomodules for particle accelerators use superconducting radio-frequency (SRF) cavities. It is known that accumulation of hydrocarbon impurities  reduces the cavity surface work function, decreasing cryomodule performance metrics such as field emission, thermal stability, and accelerating gradients. An in-situ method of plasma processing has recently been developed to clean the cavities and restore cryomodule performance. This study is to understand the properties of the 
low-pressure plasmas generated in a C100 SRF cavity and ultimately to improve the performance of plasma surface cleaning using optical emission spectroscopy. Using a 500 mm focal length Czerny-Turner monochromator coupled with a photomultiplier tube, emission spectra including the Balmer series hydrogen emission lines H_2 and H_2 of an Ar or Ar + 2% H_2 plasma at a range of 50–250 mTorr were recorded. The effects of gas composition, gas pressure, mode frequency, and input power on the optical 
emission from the plasma were investigated. This study provides important plasma characteristics and the foundation for further diagnosis of plasma parameters for future optimization of in-situ plasma processing.

Also note today there will be a seminar at 12:30 with Dallan
Duffin speaking. The zoom link was distributed yesterday,
and is different than above!

Geoff