IR FEL Monthly Report for November 1996
Navy IR Demo Contract WBS Elements
WBS 1 Project Management
November 1996 was the fifth full month of activities for the IR Demo project funded by the Navy. A total of $2,497k of costs have been obligated. With respect to the planned accrual of project cost by November ($2558k), $1627k of work was accrued which accounts for 20% of the project completed. The actual costs accrued through November totals $1844k. This results in a negative schedule variance of $932k (an increase over October of $325k) and a negative cost variance of $217k (an increase of $120k). The largest portion of the schedule variance ($568k) is in the Optics System. As explained in last month's report, we expect this schedule variance to be recovered by April '97 without effect on the total project schedule. The remaining schedule variance is accounted for in the variances in Beam Instrumentation ($216k) and Beam Transport ($163k). Additional labor is being applied to both systems to recover schedule. All other IR FEL systems have either a positive or small negative schedule variances. Additional design labor costs which have been applied to the Beam Transport and Beam Instrumentation systems account for the majority of the negative cost variance.
The $3.5M FEL Facility is still running ahead of the established
performance schedule: $1,718k of actual costs have been accrued
and the Facility is 54% complete.
Several project scheduling activities were quite active this month:
(1) a first cut schedule was drafted for all activities that
are proposed for the December shut-down of the ITS. (2) a detailed
task list for mechanical installation tasks in the IR FEL accelerator
enclosure has been completed. This will be followed by a similar
list of electrical tasks and a similar effort for the 2nd floor
of the FEL Building.
The agenda for the SURA Maritime Technical Advisory Committee
was approved for the Dec. 17-18th meeting at Jefferson Lab. A
meeting was held with DOE (Dean Helms, R. Marianelli, D. Lehman,
and J. Kearns) on Nov. 14 to discuss the planning of the February
1997 DOE Review of the FEL project. The review will focus on
building DOE mission support of the project through an emphasis
on planning for the commissioning phase and first operational
period.
Discussions were held this month with groups from the Vanderbilt
IR FEL facility, the Oak Ridge National Laboratory Solid State
Division, Argonne National Laboratory Old Dominion University,
the Army Research Office and the NASA Langley Research Center
about possible collaborations on FEL applications.
WBS 5.0 Instrumentation & Controls
Beam Instrumentation: The complete diagnostics suite has been
frozen, we have implemented a change control procedure for any
future changes. The BPM review will be held on Dec. 4. This
should clear the way for production of both the stripline and
button detectors. The mystery on the 1455 Mhz resonance is not
yet solved, but needs expeditious resolution so production can
begin. The BPM electronics are on track, more Switched Electrode
Electronics (SEE) will be ordered. The shielded beam viewer contract
is on track for delivery in mid December. The control chassis
that interfaces these units to the EPICS control system are proceeding.
The bunch length monitor from Uwe Happek (University of Georgia)
using a Michaelson interferometer is proceeding well. He will
build two units, one will be evaluated in the Injector Test Stand
(ITS). The stepper motor controller printed circuit boards (PCB's)
are complete, chassis construction is progressing. Huppek will
provide man-power to write the required software to enable the
measurement to be a single step operation.
Personnel Safety System: Procurements are proceeding, 80% of
the hardware has been delivered. The four racks are about 50%
complete. These are being built in the end of the north linac.
Machine Protection System (MPS): The hazard analysis continues.
Argonne (APS) has agreed to build and test Fast Shut Down (FSD)
PCB's and bare Machine Protection System (MPS) PCB's. These will
come with operational software drivers (minor changes to configuration
and nomenclature). The programmable high voltage power supply
was ordered to control the Beam Loss Monitors (BLM). The conversion
of this board to VME has begun.
Control System Hardware: A review was held for the computer server
& network configuration. The plan was accepted with little
changes. We will run redundant servers with mirrored disks to
prevent loss of data from a disk crash. Additionally the redundant
server configuration will allow for load sharing under normal
situations and for either of the servers to take over in the event
of a failure. The total cost matches the budgeted amount. These
components will be purchased in December. A decision was also
made to run the cryogenics IOC network and power directly from
the Central Helium Liquifier (CHL). All of the racks for the
new building have been delivered. These are being assembled in
the north linac.
Control System Software: Progress continues to be made, the software
group is working on the priorities for both FEL and work scheduled
for the CEBAF machine.
DC Power: The trim rack fabrication is 60% complete. All of
the required trim cards will be made available from CEBAF. The
BiRa scanners are being ordered. There are no significant changes
in software (other the names in the database). We are investigating
another option for the 50 Amp power supplies, the manufacturer
of our larger power supplies has a 50 Amp version which is software
compatible, and nearly 'off the shelf'. This would significantly
reduce the burden on the limited resources that are available.
Vacuum Controls: The ion pump power supplies are 50% complete.
The fabrication of the vacuum PCB's are proceeding. The crate
design will begin in December.
WBS 6 Cryogenic Distribution
Pre-installation tasks for the quad transfer line were completed.
All four sections of the tunnel supply TL are complete. We now
have 490ft of completed transfer line. Detail design of all return
transfer line modules for the FEL building are complete and have
been released for fabrication. All materials are here or on order
for all returned transfer line modules. Remaining procurements
will not impede the fabrication progress. Detail design of transfer
lines which go from the field flex can through the sleeves is
85% complete. The first sections of these lines have vacuum breaks.
All the material for the vacuum breaks is in. The CHL header
extensions were leak tested and are now complete. U-tubes at
CHL are 70% fabricated. Detail design of the warm gas lines
is 95% and procurements ongoing.
WBS 7 Beam Transport
Dipoles: Work concentrated on establishing the final design of
the three styles of Recirculation Dipoles, highlighted by a first
pass at a magnet review at mid month. After assessment of the
results of magnet measurements, the K value was fixed at 0.27
for recalculation of the final lattice. Measurements of the prototype
also revealed that length vs excitation and field flatness were
beyond the optics specifications. At month's end, a thicker field
clamp is being assessed. It will probably bring the length vs.
excitation within specification by eliminating saturation effects.
Trials of the prototype with mu metal and a Percel gap at the
pole surfaces and of (alternate technology) slots in the poles
were being prepared in order to solve the field flatness problem.
At the same time, the Northrop Grumman designer is nearing completion
of the drawing package for the saddle coil/field clamp style Optical
Chicane Dipoles, running about two weeks behind schedule. Any
of the above "fixes" can be incorporated in the package
with no difficulty. A second review is planned for early December
to resolve the issues from the first review. The designs of the
injection and extraction dipoles were firmed up. All the measurements
on the prototype dipole are now directly applicable to this other
class of dipole. Quadrupoles & Sextupoles: The prototype
weak quadrupole is finished and awaiting measurement. The prototype
sextupole is in manufacture, headed towards an on-time measurement
in mid-December. Vacuum: Significant progress was made in designing
the Injection Line X Chamber. This is the first of the many rectangular
chambers we need. The problems solved and simplifications used
on it will serve as a template for the remaining chambers. (However,
design on stands and girders for first light lagged while the
X Chamber was drawn.) Work continued on interfacing the baked
system to the non-baked system in the injector region. Emphasis
was placed on determining final quantities of commercial parts
so that orders could be placed. As of the end of the month, the
requisitions are still being prepared. Installation: Layout
of the system with respect to the building utilities ran coincident
with the determination of the cable tray locations. The exercise
resulted in the shifting many light fixture locations to miss
installed apparatus. General: The pace of the system, while
up from previous months, is still lagging behind schedule with
the outstanding peg points not taken. (Design of quadrupoles and
dipoles) Two experienced part time designers were hired to become
available December 4, a second is being obtained from Northrop
Grumman and a third is freeing up from other work. The design
pace should increase. Technical proposals for the weak quadrupoles,
which arrived on the 21st, remained unevaluated, preventing placing
the order. Reducing the cost from increases in scope still remains
an issue.
WBS 8 RF Systems
The Buncher High Power Amplifier (HPA) was successfully tested
in both local and remote control modes of operation. A short
punch list remains to be completed. The Buncher water skid and
controller were tested. They are being modified to improve reliability
and performance. The Buncher HPA will be used to drive up to 450
watts to the Chopper cavity. An iris was inserted in the waveguide
to attenuate and limit the power to the cavity. This configuration
was tested into a load. The Quarter Cryounit HPA was tested
in both local and remote control modes of operation. A short
punch list and additional software needs to be completed. The
IR FEL cryomodule control racks were tested with the 8 kW klystron
HPA. A short punch list remains to be completed. Due to an
error in the bidding process, the 225 KW variable DC power supply
was re-bid this month. The new bids are expected early in December.
The final version of the RF software was defined. It is to be
tested in December. The procurement for the waveguide flex couplings
was placed. We expect delivery to be complete in 8 to 10 weeks.
WBS 9.2 Injector Move
Bids were received for the high voltage power supply pressure
chamber that were within budget. The final bids may be slightly
higher due to the need for a few more flanges and feedthroughs.
The final drawings are being revised with the new flanges and
feedthroughs and will be sent out for final bid in early December.
We sent out preliminary bid packages for budgetary quotes on
a new clean room. The budgetary quote should be here in early
December and the purchase requisition can be submitted at that
time. Work continued on injector area layout in regards to cable
trays, lighting, and optical transport. Suggest changes in the
light positions were submitted to the building contractor.
WBS 9.4 Wiggler
The mechanical support design is at the 85% level. The optical bench is being purchased.
A contract is being negotiated with Northrop/Grumman to do the detailed design work for the vacuum chamber and chamber supports. The vacuum pumping requirements for the chamber were derived.
All the detailed drawings for the wiggler have been received and
checked. Parts are being machined at STI Optronics. The magnet
blocks for the wiggler have been delayed until January but this
is not foreseen to delay the final delivery date.
WBS 9.6 -- Optics
This month's activities were devoted to ordering most of the hardware
for the optical cavity and for optical diagnostics. Major procurements
include; a spectrograph/monochromator, sapphire mirrors for operation
at 3 microns, and a pumping system that will be used for the
accelerator as well as for evacuating the region near a cavity
mirror after it has been changed. Most of the catalog vacuum hardware
needed for the optical cavity has been received. The drawings
for the optical cavity were revised to incorporate LVDTs (to readback
the mirror positions) and ion pumps. They have been approved
for construction, and procurement will begin in December. We
have begun procurements for optical transport system components.
We ordered the tubing and the gate valves, and are soliciting
more budgetary estimates on catalog optics, the translation stages
in the mirror cassettes, and the beam dumps. A meeting was held
to discuss changes in the optical transport collimator, so we
can better adjust for differences in the thermal distortion from
different output couplers. We inspected the ground floor HVAC
penetration, and determined it will necessitate a change in our
optical transport layout. We are considering two different schemes
and should be ready to incorporate them in December, when we will
have designer support.
Injector, SRF, Facility, and Other
Activities Outside Navy IR Demo Contract
Injector Test Stand (ITS)
During November, the gun was commissioned and operated at 250
keV. In general, difficulties surfaced where they were least
expected -- in the drive laser. In an effort to stabilize operation
of the drive laser and suppress ghost pulses in the electron beam,
we upgraded a number of components, including electro-optic modulators,
mirror mounts, and lamps. We then ran the gun routinely, going
to two-shift operations. After ascertaining that a top-hat-like
transverse profile proved optimal for reproducibility, we extracted
a full set of publishable data in support of a doctoral candidate's
dissertation. This data is tailored to validate the computer
code used to simulate the electron-beam dynamics in the gun.
By the end of the month, plans were to attempt operation of the
gun at higher voltage, up to 300 keV, prior to shut-down for installation
activities and replacement of the high-voltage stack, and to do
further upgrades to the drive laser during the shut-down period.
Progress continued toward fabrication of a replacement high-voltage
stack that would allow routine, long-term operation at 350 keV.
We decided to focus on producing two new ceramics of well-matched,
higher electrical conductivities, in anticipation that the higher
conductivities would raise the threshold for arcing caused by
electrons embedded in the ceramics after field emission from metallic
components. By the end of the month, the production of these
ceramics was about three weeks behind schedule, due principally
to uncertainties in the measurements of the conductivities. At
this writing (3 Dec. 96), the stack is projected to be ready on
23 Dec. 96. We are partially compensating this delay by shuffling
the installation schedule in the Injector Test Stand to move installation
of the stack from the first activity (as initially planned) to
the last activity. Other installation activities include putting
the cryounit in the test cave for off-line high-power rf tests,
placing stands and girders in the cave for the 10 MeV beam line,
and installing the beamline for the 350 keV experiments.
Other ITS progress included successfully completing the fabrication
and acceptance tests of the cryounit, the buncher cavity, and
components for the 350 keV experiments. Comprehensive plans for
the 350 keV experiments were also compiled and posted on WWW.
Details are discussed in the weekly reports. Much of the activity
involving beam physics was focused on refining the design of the
transport lattice in conjunction with measurements of magnetic
field profiles in the prototype dipole magnet, and the design
of the vacuum chamber to allow for installation of the array of
electron-beam diagnostics in keeping with the impedance budget.
By month's end, sufficient information was available to work
toward freezing the top-level design drawing and the lattice.
Plans are to include a design of the second recirculation arc
that will facilitate a future upgrade to a 75 MeV machine to generate
1 micron light, as well as to add of order 1 m extra length after
the cryomodule to enable multipass monitoring that will facilitate
machine operations. We anticipate freezing the design by mid-December,
at which time we will institute a formal change-order process
for proposed revisions. Such a process is already in effect for
the diagnostic suite, and it is working smoothly.
A concerted effort was launched to study, by way of computer simulations,
the bunch dynamics from the photocathode through the optical
chicane, for all operational modes of interest, i.e., both for
first light and for full-current operation. The accelerator layout
used in the code was updated to reflect the latest configuration
since there have been numerous changes in detail over the past
few months. Simulations performed by month's end indicate favorable
bunch profiles for all peak currents of interest. Computational
results concerning the degree of bunching in the optical chicane
are in general agreement with analytic predictions based on the
longitudinal envelope equation.
Work on the influence of coherent synchrotron radiation (CSR)
on the electron-bunch dynamics in magnetic bends has continued.
We discovered that localized radiation and coulombic fields in
the bunch have the potential to make important contributions to
the transient bunch dynamics. Previously we had ignored these
fields believing that they were negligible compared to the long-range
influence of CSR. It turns out that this statement is true after
long times, but the local fields can be more important on short,
but still macroscopic, time scales. We are now upgrading our
analytical and numerical analyses to include all of the local
fields. The radiative transients have proved to be much more
intricate than we originally suspected. The coulombic and radiative
transients tend partially to offset one another; we are in the
process of trying to formulate general qualitative predictions
about these complex phenomena.
WBS 3 Cryomodule
Cryounit acceptance testing has been completed. Data reduction
indicates optimum operating fields of 11MV/m and 9 MV/m for the
first and second cavities respectively. The quality factor of
the second cavity is depressed and will produce an additional
2 K heat load of 30 watts during operations at 9MV/m. The bridging
cylinders order has been placed, finishing all bridging component
procurement starts for the linac cryodmodule. The cavity pair
beam line isolation valves and acceptance testing is complete,
all valves have been accepted and waiting final dimensions from
cavity interfaces. Four cavities have had final machining completed
on interface flanges and are ready for final warm tuning. The
intermediate beam tubes for these cavities are complete and dished
head assemblies are in final fabrication.
WBS 2 Beam Physics
Much of the activity involving beam physics was focused on refining
the design of the transport lattice in conjunction with measurements
of magnetic field profiles in the prototype dipole magnet, and
the design of the vacuum chamber to allow for installation of
the array of electron-beam diagnostics in keeping with the impedance
budget. By month's end, sufficient information was available
to work toward freezing the top-level design drawing and the lattice.
Plans are to include a design of the second recirculation arc
that will facilitate a future upgrade to a 75 MeV machine to generate
1 micron light, as well as to add of order 1 m extra length >after
the cryomodule to enable multipass monitoring that will facilitate
machine operations. We anticipate freezing the design by mid-December,
at which time we will institute a formal change-order process
for proposed revisions. Such a process is already in effect for
the diagnostic suite, and it is working smoothly.
A concerted effort was launched to study, by way of computer simulations,
the bunch dynamics from the photocathode through the optical chicane,
for all operational modes of interest, i.e., both for first light
and for full-current operation. The accelerator layout used in
the code was updated to reflect the latest configuration since
there have been numerous changes in detail over the past few months.
Simulations performed by month's end indicate favorable bunch
profiles for all peak currents of interest. Computational results
concerning the degree of bunching in the optical chicane are in
general agreement with analytic predictions based on the longitudinal
envelope equation.
Work on the influence of coherent synchrotron radiation (CSR)
on the electron-bunch dynamics in magnetic bends has continued.
We discovered that localized radiation and coulombic fields in
the bunch have the potential to make important contributions to
the transient bunch dynamics. Previously we had ignored these
fields believing that they were negligible compared to the long-range
influence of CSR. It turns out that this statement is true after
long times, but the local fields can be more important on short,
but still macroscopic, time scales. We are now upgrading our
analytical and numerical analyses to include all of the local
fields. The radiative transients have proved to be much more
intricate than we originally suspected. The coulombic and radiative
transients tend partially to offset one another; we are in the
process of trying to formulate general qualitative predictions
about these complex phenomena.
WBS 4 Commissioning/Operations
WBS 4 -- IRFEL COMMISSIONING
Most of the activity centered on developing commissioning plans leading to first light. Commissioning plans were drafted for the injector from photocathode to injection-line dump, and the accelerator through the straight-ahead dump. A proposed FEL turn-on procedure was also drafted and is presently being discussed. As a result of these activities, there have been some changes to the diagnostic suite, to include addition of a few beam-position monitors, relocation of one of the multislit transverse-emittance diagnostics, and addition of synchrotron light ports to the optical chicanes. Additional considerations of commissioning for energy
recovery resulted in adding a cavity-based path-length monitor.
The totality of these activities also led to further consideration
of the dump-line designs. Only one dump-line design remains to
be solidified, that of the energy-recovery dump, and the associated
work is currently underway.
We decided to base the IR FEL machine protection system (MPS)
on that of Argonne National Laboratory's Advanced Photon Source
(APS). The APS system has been operating successfully for three
years under EPICS, which is the control software used at Jefferson
Lab.
A standardized set of IR FEL operating modes was tabulated, circulated,
and posted on the WWW. The operating modes are compatible with
present plans for the MPS. They also constitute a set of basic
requirements for subsystems of the accelerator.
Facility
During this month the lower level of the building was completely
enclosed with the completion of the 3' thick interlevel concrete
pour. The fixes on the RF waveguide penetrations were completed
and the walls around the interlevel were also finished. The interlevel
surfaces were sealed and sand and rock fill begun in the interlevel
areas. Filling was also done around most of the north and west
of the building bringing the level up to ground level or above.
This will aid in the insulation and drying of the concrete in
the enclosure so painting can take place. Initial pours of the
truck ramp were completed and the lobby/loading dock area excavated
and leveled. HVAC installation was initiated.
Layouts of the cable tray and Jefferson Lab installed utilities
were produced. A minor rework of lighting positions was sent
to the contractor optimized for our current accelerator layout.
The injector layout was redone to accommodate the new planned
HV tank for the injector power supply. A layout which allows
the easiest cryounit access was established. Rack layouts upstairs
were finalized and layout drawings with rack and penetration identification
were produced. Estimates were requested from several vendors
for the new clean room. Communications plans were finalized for
control between the CEBAF Machine Control Center and the FEL Facility.
Work on the cable database was initiated and several WBS elements
ordered their cables packages. Bids were solicited for commercial
surveyor support during initial network generation.
Upcoming Meetings and Reviews
Maritime Technical Advisory Committee Meeting Dec. 17-18, 1996
Laser Processing Consortium Workshop Jan. 21-22, 1997
SPIE High Power Light Source Conference Feb. 8-14, 1997
DOE Basic Energy Science Review Feb. 24-25, 1997