NMR Einzel Lens EL3 New Set of Tests - PowerPoint PPT Presentation

Loading...

PPT – NMR Einzel Lens EL3 New Set of Tests PowerPoint presentation | free to download - id: 123244-OWM1O



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

NMR Einzel Lens EL3 New Set of Tests

Description:

Starting Pressure was about 3. 10-9 Torr. Images with Ion-Gauge Light. Aluminum shutter ... After the tests the vacuum was worse ~ several 10-8 Torr ... – PowerPoint PPT presentation

Number of Views:34
Avg rating:3.0/5.0
Slides: 12
Provided by: dela94
Learn more at: http://trshare.triumf.ca
Category:
Tags: nmr | einzel | el3 | lens | new | set | tests | torr

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: NMR Einzel Lens EL3 New Set of Tests


1
ßNMR Einzel Lens EL3New Set of Tests
Andrew MacFarlane, June 30, 2004
2
On 30 June 2004, we had everything pumped
and conditioned well enough to proceed with more
tests of the EL3 discharge.
With the closed EL3 / Solenoid system (gate valve
closed) Pumped by 2 cryopumps and the EL3
coldhead.
Starting Pressure was about 3. 10-9 Torr
3
Images with Ion-Gauge Light
  • Aluminum shutter
  • protects sample during
  • HV conditioning

Sapphire Scintillator 19.8 mm diameter Replaces
former BC412
Note Camera is well-focused
4
First Result Sapphire makes more light than BC412
EL33kV, BIAS30kV, B3T
BC412
a-Al2O3
11 second exposure, no contrast stretches
5
Second Result Delayed Discharge Turnon
To see if we could reproduce the light we saw
previously we went back to the same conditions,
namely
EL33kV, BIAS30kV, B4.9T
The first few images remained dark (really dark)
11sec exposure AND one contrast stretch
In an effort to see any light, we turned EL3 to
10kV, and there it was very bright
6
Third Result Sharp Threshold of EL3 Voltage to
Start Discharge
B3T and BIAS30 kV
EL3 at 2.5kV no light even
after 5 minutes
EL3 at 2.7kV bright light
after 30 sec
i.e. threshold 2.6kV
B3T and BIAS15 kV
Threshold increased to between 3.5 and 5 kV
7
Fourth Result Persistence of Discharge after EL3
turned off
0kV,3T,30kV
Turn EL3 to zero (or off)
Same image, one contrast stretch
8
Persistent Discharge
Lasts at least 10 minutes under these conditions
Disappears if BIAS is turned to zero
9
Fifth Result no discharge with negative EL3
voltage
With a 5kV supply from Mike, we tried 5kV and
2.5kV, and the image remained dark after 5min
Not totally!
Both images have one contrast stretch, 11sec
exposure
10
Bias Sparks do not give light
The conditioning was not perfect and occasionally
the platform Bias would spark V would drop and
recover. Images taken during such spark events
did not show a noticable increase in light
11
Vacuum
During the tests we had the ion gauges off
because they produce too much light. After the
tests the vacuum was worse several 10-8
Torr We did not go ahead with pressure
dependence tests since time ran out
About PowerShow.com