View source for Vacuum chamber


== Done ==

* 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


== 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]