Difference between revisions of "Vacuum chamber"

Latest revision as of 11:36, 31 March 2022

Remove WP-1250 NEG cartridges
Remove posts for woven metal screen and replace with something suitable for high vacuum
Add (tack weld?) fixtures to the vacuum chamber for S&A tooling
Send vacuum chamber to S&A for fiducial (locate top flange, and anode flange with repost to chamber z-axis.
Clean vacuum chamber (wipe off with iso-propanol, removed foreign objects, etc)
Consider replacing the WP-1250 NEG cartridges with modern UHV 1400 NEG wafer modules (~12 week delivery)
- If using UHV 1400 NEG wafer modules, no screen is necessary
- Marcy to calculate how many UHV 1400 NEG wafer modules are needed, based on this, we'll develop a scheme to mount them. No need for a shield screen if e go with this modern NEG wafer modules. Need to figure out how to win them inside the vacuum chamber, and likely built a new power supply.
If the old WP-1250 modules stay:
- Bubba to finish new woven metal screen
- Devise a better method to hold the screen in place
- Devise a reliable method to prevent electrical short in the NEG cartridges electrical connections for full activation with current
Re-install extractor gauge

Gun chamber cleaned, blown down with ionized nitrogen
UHV1400 pumps installed and connected to feedthrough
First bake: 48 hours at 250C. No NEG activation. Leak in extractor gauge opened on ramp down
Second bake: 24 hours at 250C after vent for extractor swap. P vs. T data taken for ~2 weeks
Third bake: 48 hours at 250C, NEG activated for 1 hour at 500C while chamber at 200C. Vacuum tests underway 31march2022

Finish vacuum qualification (~April 15)
Fabricate and install shield screen
- Finalize design (April 8)
- Order parts: standoffs, more screen, shimstock strips? (April 8)
- clean and heat treat materials (April 18 or 25)
- install screen (April 25 or May 2)
Send gun assembly to clean room for inversion, nitrogen blow-down. week of May 2?
Install spider and anode, align
Install electrode, align

@@ Line 1: / Line 1: @@
+== Done ==
 * Remove WP-1250 NEG cartridges
 * Remove posts for woven metal screen and replace with something suitable for high vacuum
@@ Line 12: / Line 15: @@
 ** Devise a reliable method to prevent electrical short in the NEG cartridges electrical connections for full activation with current
 * Re-install extractor gauge
+== vacuum qualification of chamber ==
+* Gun chamber cleaned, blown down with ionized nitrogen
+* UHV1400 pumps installed and connected to feedthrough
+* First bake: 48 hours at 250C. No NEG activation. Leak in extractor gauge opened on ramp down
+* Second bake: 24 hours at 250C after vent for extractor swap. P vs. T data taken for ~2 weeks
+* Third bake: 48 hours at 250C, NEG activated for 1 hour at 500C while chamber at 200C. Vacuum tests underway 31march2022
+== Steps for completion ==
+* Finish vacuum qualification (~April 15)
+* Fabricate and install shield screen
+** Finalize design (April 8)
+** Order parts: standoffs, more screen, shimstock strips? (April 8)
+** clean and heat treat materials (April 18 or 25)
+** install screen (April 25 or May 2)
+* Send gun assembly to clean room for inversion, nitrogen blow-down. week of May 2?
+* Install spider and anode, align
+* Install electrode, align
 [https://wiki.jlab.org/ciswiki/index.php/18%22_Photogun_ala_GTS Back to 18" Photogun page]