From: William Blanchard [wblanchard@pppl.gov]
Sent: Monday, September 09, 2002 1:39 PM
To: wreiersen@pppl.gov
Cc: hkugel@pppl.gov; mzarnstorff@pppl.gov
Subject: GRD Comments

Wayne,   A few comments on the GRD.   -Bill

3.2.1.1.2.1 Base Pressure: The initial surface area of the vacuum vessel for first plasma will be approximately 40 M^2 and will be increased significantly in its final configuration. All materials in vacuum should be high vacuum compatible. With a target leak rate in the range of (1-2)x10-5 T-l/sec or less and a pumping speed of 2600 l/sec or better and a well baked and conditioned machine, the device should produce a base pressure in the low 10-8 Torr of impurity gases at 293K. All diagnostics that are not to be left open permanently to the vacuum vessel should have their own pumping system and all appendages, ports and diagnostics should have bakeout capabilities to maintain very high vacuum conditions. All systems and components either in vacuum or with a vacuum interface should be designed to preclude trapped volumes and virtual leaks.

3.2.1.1.2.2 Pumping Speed: delete "which is equal to or greater than that achieved on PBX-M."

3.2.1.2.1.1 Bakeout Background: Suggest that it be pointed out that all systems and materials be compatible for the bakeout temperature they will see for strength, compliance for expansion and vacuum compatibility (developing leaks etc.).

3.2.1.2.1.2 Glow Discharge Cleaning (GDC)   (delete During Bakeout)a) The facility shall provide a glow discharge cleaning (GDC) capability with DC glow for indefinite periods of time with the vacuum vessel and all components internal to the vacuum vessel at room temperature and at their nominal bakeout temperatures. All windows should have shutters to prevent coating during GDC. All large ceramic breaks should be shielded to prevent coating and high resistance shorts between different grounds.

3.2.1.4.4 PFC Configuration d) delete "sealed"

3.2.1.4.7.2 Gas Injection. The gas injection system shall be capable of injecting any one of three gases (or combination of gases) with a maximum flow rate of at least 50 T-l/sec per injector. The device and facility shall have a programmable gas injection system with feedback on real-time density measurement.

3.3.1.2 Vacuum Compatibility. a) In-vessel metallic components shall be electropolished when feasible b) All in-vessel components shall be degreased and cleaned as a minimum and baked when practicable prior to installation.c) All in-vessel materials shall be approved by the Project for vacuum compatibility [3].

3.3.6 Environmental, Safety, and Health (ES&H) Requirements. Somewhere in this section it should state that all vacuum windows of 4" or greater shall have covers over them or otherwise be protected from accidental implosions.


A few questions/comments:[1] What are the standoff voltages that systems are to be designed to? [2]What is the grounding scheme? [3]What loop resistances can be tolerated? [4]How are they going to be monitored? [5]Some systems should be designed with ease of removing grounds for troubleshooting loop faults (diagnostics, thermocouples etc).[6] It might be helpful for new drafts to have the changes that were made in a different color to expedite subsequent review.