Injector Test Stand Meeting Minutes of December 10, 1996

and Reports of December 13, 1996

AGENDA:

General Announcements

Action Items

Progress Toward the Milestones of the enclosed schedule:

NOTE: Meetings are held every Tuesday in CEBAF Center, Room #A110, at 11 a.m., unless otherwise notified.

ATTENDEES: M. Augustine, S. Benson, G. Biallas, C. Bohn, D. Engwall, J. Fugitt, D. Guilmet, K. Jordan, R. Legg, G. Neil, J. Preble, M. Shinn, T. Siggins, R. Walker, M. Wiseman

NOTE: A reminder to all principals to submit a brief weekly progress to D. Gilchrist each Friday by noon

General Announcements:

There will be a safety review of the Injector Test stand safety systems by the RCG at 1:00 today.

Decisions/Comments:

Several items didn't fit or were not ready when the change-out began. We will try again to institute procedures to enhance quality and speed up the work. G. Biallas and M. Wiseman have agreed to start out each project with a requirments document followed by a kick-off meeting at the 5% stage that will bring in the customers at the start. Near the end of a design we will be more active in checking our work. Members should be more forthcoming on the status of their projects at this meeting. It is the a way to get more resources to bare on the most critical items.

Safety Action Items:

K. Jordan - Add a third sensor for ODH to the High Voltage room. Will be done during Change-over.

J. Fugitt, C. Reese, K. Jordan - Review the safety effects on our systems of running only one HPA for work in the Cryomodule Test Cave. In process but not needed until at beam is used in the cryomodule. No progress.

RCG - Review the beam containment policy and the Machine Protection System during October. R. Legg reports he is waiting for RCG action. See notice of meeting today.

Rich Hill - Label the gas lines with media and pressure - No progress

G. Biallas - Provide safety hardware for the shelf by the LCW system. No action.

New Safety Action Items:

None.

Completed Safety Action Items:

M. Shinn - Excess boxes on cabinets. Complete.

Action Items:

G. Biallas - Make a new ceramic stack and make a new cathode support tube with a anti field emission coating. See Discussion and weekly report by G. Biallas.

Determine the need for additional personnel required to match or beat the Schedule. None

G. Biallas - Finish the LCW System: Flow & Temp reading, Level indicators, Full qualification walk through needed. Remove two carbon steel pipes inside LCW system. J. Fugitt wants to check calibration on the conductivity gages. Walk through will be tomorrow.

K. Jordan/S. Benson - Failure analysis for the 10 MeV beam handling. Required by Dec. 1. No show stoppers showing up. BLM hardware available this week

R. Legg - Write the OSP for the 500 keV Experiment with chopper on and cryomodule in the cave. and for the 10 MeV Experiment. Ready for sign-off.

M. Shinn - Define a secure procedure for turning on the Drive Laser from the control computers. No action.

J. Preble - Get the ceramic windows finished for the December Quartercryomodule tests. One is on hand . Brute force style window in preparation because the first hasn't been duplicated.

K. Jordan - Design a new viewer system with stable cameras and appropriate windows. At the same time avoid stray light back to the Cathode. Being done during change-over.

R. Walker/K. Jordan - Substitute stainless steel for the aluminum filament supports on the harps. Still needs work during the change-over..

M. Shinn - Perfect the optical chopper before the next CW run. Needs refinement for more demanding runs. Good progress.

G. Biallas - Get drawings prepared of the configuration of the gun for the control room and a summary package that can be sent to others as an explanation of what the gun is. No action.

K. Jordan/M. Shinn - At Change-over, install a method of characterizing the optical transport line configuration at any one time and conveying the information to operators. In process.

L. Dillon-Townes - Get the core for the solenoid before the Quartercryomodule for the 10 MeV Run. Drawings need sign-off.

G. Biallas - Identify and sequester the raster magnet for 10 MeV as well as all the remaining magnets. Sextupole is changed to 3 hp, 3 phase motor stator - needs characterization. Several QJs need alingnent bushings before measurement.

L. Dillon-Townes - Convene change control board to make a recommendation on the Differential Pump Station and the question of baking the after Cryomodule line in both the ITS and the IRFEL after doing the necessary calculations of assumed gas load. Review continuation on Tuesday, Dec. 24 at 1:00 pm.

New Action Items:

G. Biallas - Get Schedule up to date.

New Action Items for the Diagnostic Mtg.:

None

Completed Action Items:

G. Biallas - Get the strong back certified to lift blocks by Nov. 1. Complete. standard SB Sextuple should do it.

L. Dillon Townes - Get the layout drawing for the installation of the off line Quartercryomodule signed off. signed.

G. Biallas - Plan on what blocks to lift out for November change out. Complete.

Biallas/Siggins - T. Siggins to try out Solenoid in order to verify it fits on Chopper. Complete.

L. Dillon-Townes - Get the dump body flow tested. No action. Needs to be restricted to limit velocity below 10 ft. per sec. Cancelled

All principals - Define the tasks for the change-over down and convey them to D. Walker. to get a master list going. Complete.

R. Legg - Check the alignment accuracy specs. of +- 1/3 mm for the Longitudinal experiment and the 10 MeV experiment. Complete.

K. Jordan/R. Legg - Convene a working session in December on control software for the 10 MeV Run. Complete.

Individual Reports of 12/16/96:

Bob Legg/R. Walker:

Installation activities in the ITS are proceeding on schedule, and are being closely coordinated to keep them on schedule. The most noteworthy accomplishment of the week was removing the roof, inserting large components including the cryounit, beam dump, and assorted stands and girders, and then replacing the roof. Work is also proceeding on upgrades to the photocathode drive laser and its optical transport system.

G. Biallas:

Resistance measurements of the new ceramics that had initially been done at HiTemp in California were done under a nitrogen purge. They indicated success in that the required resistance values were obtained after application of a second spray-and-bake coating of chromium sesquioxide and vanadium pentoxide on the new batch of ceramics containing 3% glass in the aluminum oxide. However, subsequent readings were erratic. None of the resistances matched within 50%. This lead us to make measurements using a vacuum chamber at the College of William and Mary. After taking data last weekend, and upon confirming our measurements during the week, we are convinced that we are not obtaining the desired 10^9 to 10^10 ohm from the coating on the new ceramic insulators. Rather, the ceramics exhibited resistances on the order of 10^13 to 10^14 ohm, approximately the measured bulk resistance of an uncoated ceramic.

To compare, we made measurements in vacuum on a spare coated ceramic from the original batch, i.e., one from the same generation as the ceramics in the 250 keV gun, and obtained mixed results. The measurement yielded resistances of 6x10^10 ohm up to 40 kV. Thereafter, up to the test limit of 50 kV, the reading changed to the 10^13 ohm value of the new ceramics. The reading then reversed itself at 10 kV, and these observations held under three repetitions. We plan to measure one of the ceramics in the gun when we open it up to see if we can reproduce these measurements.

In summary, the data on the new coated ceramics unambiguously indicate that the coating offers no significant improvement in electrical properties, with the exception that both the new and original ceramic coatings still provide for significant suppression of secondary electron emission from the ceramic surfaces by lowering the secondary emission coefficient of pure alumina. Thus, the chief benefits of the new ceramics are restricted to a lower propensity to crack or puncture, properties that arise as a consequence of the higher percentage of glass phase.

In view of our findings, we decided that it is not worth further delaying the gun schedule to accommodate a new ceramic stack. Rather, we are reverting to our back-up plan of commissioning FM Technologies to apply their coating, known to suppress field emission significantly, to the entire cathode support tube. We will then use it to replace the tube presently in the gun, and we will keep the existing stack in the gun. This strategy should enable completion of the "new" gun by mid-January.

In parallel, we will construct two new high-voltage ceramic stacks, one using two of the new ceramics, and another using two new ceramics with an ion-implantation coating done at UC Berkeley. These stacks will then be stored should they be needed in the future.

R. Walker - 12/6/96:

A waveguide aperture was built and tested to produce 10 dB of attenuation so that the Buncher klystron can be used to drive the Chopper cavity. This will provide up to 450 watts to the cavity.

The Buncher water skid has been modified to provide a cavity temperature and improved water flow. A replacement valve for the water skid is due 12/15/96.

New downloadable code is at test for the Buncher. The Chopper code will be part of the Buncher. Screens will be available in a few weeks for both the Chopper and Buncher.

Bids for the new 225 KW variable power supply were received this week. They are being evaluated now.

The P.O. was placed for the waveguide flex couplings. They are due to be received by 4/1/97.

The following is the status for the ITS Test Cave tasks:

a) completed layout for the 50 KW dump and part of the 10 Mev line.

b) installed stands for part of the 10 Mev line.

c) installed dump shield frames and shields.

d) prepared LCW pipes to dump.

e) moved Buncher waveguide.

f) vented beam line to nitrogen and covered.

g) Chopper mounts needs correct hole placement.

h) Diagnostic chamber needs to be welded and leak tested.

i) parts for the new aperture need to be made for assemble later.

j) fluorescent lights and mounting brackets in the Test Cave need to be moved.

k) 50 KW dump cooling system was postponed until January or February of 1997.

l) the resistance of the gun ceramics have not yet been measured at high voltage.

R. Walker - 12/13/96:

Waveguide sections are being made in the Machine Shop for the Quarter cryomodule. The waveguide sections for the Chopper are ready for installation.

A replacement valve for the Buncher water skid is due 12/16/96. A M-460 CAMAC card needs to be repaired so the cavity water temperature can be read.

New downloadable code and screens are at test for the Buncher. The Chopper code will be part of the Buncher.

The contract for the new 225 KW variable power supply was placed this week with Hipotronics. They expect to meet our required delivery date.

The following is the status for the ITS Test Cave tasks:

a) Chopper and solenoid, after several modifications, are installed on the beam line.

b) Quarter cryomodule is positioned off-axis awaiting the correct warm windows.

c) Diagnostic chamber needs to be welded and leak tested.

d) New aperture was modified again and is ready for assembly.

e) Stainless steel harps need to be made, heat tested, and assembled.

f) Stands for 10 Mev experiment are installed and aligned.

g) 50 KW dump cooling system was postponed until January or February of 1997.

h) Ion pumps will be moved into the cave when they are needed.


Enclosures:

ITS Schedule for 12/17/96