MEMORANDUM
To: J. Albertine, D. Helms, W. Skinner
cc: Division (M7), FEL Coordination Group
From: F. Dylla
Subject: IRFEL Weekly Report, September 15-19, 1997
Date: September 19, 1997
Management
Installation and subsystem commissioning activities proceeded
this week at a rapid rate. Highlights include: installation
of all eight of the optical chicane magnets, successful testing
of 50kW and buncher FR systems, and installaiton of all of the
required DC power supplies.
Jefferson Laboratory's annual Science and Technology Review was
held this week (Sept. 17-19) as a required component of SURA's
contract with DOE to operate the laboratory. Two members of the
seven person review committee focused on the FEL program. Good
marks were received on the execution of IR Demo construction project,
including resolution of issues that were identified at the mid-project
DOE review in February. The recent attention given by the FEL
Program Management was encouraged to continue to develop basic
science applications which complement the existing industrial
and Navy applications.
An agenda for the Oct. 2-3 IR Demo construction project close-out
meeting was forwarded to Navy High Energy office and DOE Site
Office.
On Tuesday, Tony Favale and Alan Todd from Northrop Grumman visited
the laboratory to discuss continuation of our collaborative R&D
activities for next year.
Accelerator Systems
Regarding the beam-transport system:
The optical chicane dipoles were installed and fit well around
their vacuum chambers. The Injection/Extraction dipoles are going
through hall probe measurement where field clamps are adjusted
to bring all units within the required field integral. Bore gage
readings revealed that two DUs have poles with variation in the
mu metal/brass/adhesive thickness at .003 inch, greater than the
specified .002. We arranged for a re-glue by Everson.
Tom Schultheiss from Northrop Grumman constructed a magnetic model
in TOSCA of the DV dipole and the 10 MeV line that is adjacent
to it. At week's end, the model was working, but not verified
with data from magnet measurements. Robin Wines took over the
use of the model and of finding a solution to shielding the 10
MeV beam line while still providing uniform field integrals through
the good field region.
Everson has started final assembly of the four DX style reverse
bends and completed gluing the mu metal and brass on pole tips
for two of four of the other style of reverse bends, the DQs.
Everson also received the contract to assemble the 180 Degree
Dipoles (DYs) this week. The agreement contains a provision to
prove out the process of gluing segmented mu metal and brass using
bolts and the pole slabs themselves. The time devoted to this
development will retard the final assembly of the last 180 degree
dipole until mid November.
Progress in finishing the system is also being restricted in the
magnet measurement area. It remains full occupied in measuring
DU/DV dipoles. We will continue to advance the assembly of the
entire beam transport system in the arcs by an arrangement with
Everson, postponing the final assembly of the DQ reverse bends
and substituting a trial assembly of the parts for the second
180 degree dipole. It will have filler pieces substituted for
the mu metal/brass. We will install this trial assembly magnet
as well as two of the unmeasured DX dipoles and the pole tips
from a DX and a DQ (poles that were machined by the vendor as
production spares) onto their respective stands in the first arc.
This assemblage is a base on which we can fit-up the entire seven
or eight segments of the vacuum chambers for the two arcs before
final cleaning. There are no bellows between segments and such
a fit-up will be invaluable for smooth final assembly. Everson
will continue final assembly of the DQ and assembly of the first
180 Degree Dipole in parallel with the chamber fit-up. George
Biallas visited Everson on Friday.
In the quadrupole and sextupole area, winding of coils and machining
cores for the eight Panofsky trim quads continued at Magnet Enterprises
International (MEI).
In the corrector area, manufacture of the coils for the phasing
dipoles (DGs) continued at MEI. Contrary to what had been reported
earlier, the manufacture of their mu metal cores was not started.
The contract was delayed by arm wrestling over fine points associated
with this sole source procurement. Fabrication of coils for the
reverse bend correctors continued at Advance Magnet Lab (AML).
The air core corrector contract was awarded to AML with first
articles promised in two weeks and the final delivery slated for
8 weeks ARO. Manufacture of the to prototypes needed for the
injector line continued with all coils wound and potting ready
to begin.
The chambers for the first of four reverse bends are complete
and are awaiting completion of the cross for the beam scraper
to be bolted together. Welding of ends on to bodies continues
on the remaining reverse bend chambers. Welding on the 180 degree
chambers started at Master Machine, anticipating delivery around
Sept. 29.
Two power supplies for the injection and extraction dipoles were
installed in their racks, completing installation of the required
inventory of DC power supplies for the system.
Regarding RF systems:
The two 50 kW klystrons were operated without difficulty in the
FEL Facility, one to 45 kW and the other to 55 kW. In addition,
the buncher cavity was powered to its full-rated value of 2.5
kW.
Preparations for turning on the photocathode gun proceeded in
earnest throughout the week. Testing of its high-voltage power
supply gun was completed from the FEL Facility control room.
Fit-up of the vacuum tank and elbow that connects the gun to the
high-voltage stack was also completed today (19 Sep 97). An additional
1" spacer was needed and will be available Monday morning;
our Machine Shop will make it by cutting a hole in an existing
blank-off flange.
Regarding instrumentation and control systems:
Major activities center around preparation for high voltage conditioning
of the gun and injector beam next week. The controls interface
for operating the high voltage power supply from the control room
are complete. The voltage and current readbacks are connected
through EPICS as well as being patched to the table top. These
signals are also available on the projector for ease of viewing.
The laser shutter control is also being worked.
The Personnel Safety System was recertified this week, one last
step is to connect to the gun high voltage power supply for gun
conditioning early next week. This system is fully operational
from the Accelerator Main Control Room.
The trim magnets are connected and ready for the injector beam
line, the balance continue to be connected. The vacuum system
is also staying ahead of the installation activities. As the
beam line is evacuated, the ion pumps can be brought on line.
The EPICS vacuum control screens may be ready next week.
The HP workstations are being setup in the control room and user
labs. The server conversion will happen on Monday; the injector
test stand server will be decommisioned and the entire load will
be on FEL1 and FEL2.
The (prototype) VME buffer board for the video multiplexing system
is complete and documented. This is now being used to commission
the EPICS software and control screens. The initial beam test
do not require the mux but it may be ready.
Documentation, cable, parts, & boards continue to arrive for
the Analog Monitoring System (AMS). The mux is identical to the
video system so it's making great progress as well.
The work in Hall B is finishing up so the personnel has returned
to complete OTR foil assemblies, and viewer installation. The
BPM cabling and electronics installation continues to move ahead.
FEL Systems
Injector Reinstallation
The gun bake was completed successfully and hookup of the beamline
elements is started. The high voltage tank was mounted on the
gun. The high voltage supply was tested to 350 kV in 14 PSI of
instrument air. It is now being fitted up to the gun. The supply
can now be controlled and monitored from the FEL control room.
The final stand for the optical transport was received and installed.
The last two mirror cans were installed and aligned.
Wiggler
All the flanges were welded on the wiggler vacuum chamber. The
chamber is ready for leak check and, if necessary, straightening.
It will be fitted up to its support next week.
Optics
Components for the mirror cassettes were awarded this week. Components
for the bodies went to Master Machine. The linear stages that
go in the mirror cassettes was also awarded. The last mirror
cans have been hung with modifications made to make them fit.
Beam should be delivered to the light box next week. Modifications
to the clean room chilled water system are also being made.
Commissioning/Operations
A draft of the complete injector setup procedure is now available
and is posted on the www at http://www.jlab.org/~legg/procedures/Injector_setup_proc.pdf.
We will be refining it over the next two weeks. In addition,
the Magnet Performance Integration Plan is published as a Jefferson
Lab technical note, TN-97-034. It, too, can be viewed on the
www at the technote page of www.jlab.org/~douglas.
Detailed analysis of the longitudinal emittance data from the 350 kV gun experiments conducted over the last weeks of the Injector Test Stand Program is now essentially complete. The analysis strongly suggests that there was an error in the measurement of the bunch charge for the long pulse, high current setup. Specifically, simulation (PARMELA) results closely match the phase-space data if the input bunch charge is 175 pC rather than the 135 pC measured with the picoammeters. Accordingly, we will pay special attention to bunch charge measurements as we commission and operate the gun in the FEL Facility. It is difficult to infer a precise value for the rms longitudinal emittance in the ITS experiments because the measurement is dominated by uncertainties caused by finite slit size. However, an upper bound is 44 keV-deg at 175 pC bunch charge, which compares favorably with the 50 keV-deg required at the wiggler, although if the upper bound is close to the real value, there is little margin. Nevertheless, all indications are that gun operations at 350 kV produce an electron beam with phase-space properties that meet requirements.