MEMORANDUM

To: J. Albertine, D. Helms, W. Skinner

cc: Division (M7), FEL Coordination Group

From: F. Dylla

Subject: IRFEL Weekly Report, August 11-15, 1997

Date: August 15, 1997

Management

Highlights for the week include installation of the 10 MeV dump hardware and connection of the cryomodule instrumentation in preparation for cool-down later in the month. Low conductivity water is now flowing through all the RF systems.

Management attention was focused on closure of the July financial reports for the project and set-up of accounts for the use of the commissioning/upgrade funds which were released to the laboratory last week.

Scheduling activities are focused on carefully integrating the remaining installation tasks with the start-up of commissioning tasks. Installation tasks are being phased such that remaining installation tasks will have little or no impact on the first commissioning tasks which will proceed from the gun to injector cryounit to linac cryomodule to wiggler to recirculation arc.

Final preparations were concluded this week for the project's presentations at next week's International FEL Conference in Beijing. The following papers will be given by project staff:

"Status Report on Jefferson Lab's High-Power Infrared FEL" - C. Bohn

"Progress on the Study of Emittance Growth Induced by Transient Self-Interaction of a Bunch Entering a Bend" - R. Li

"Experimental Results from a DC Photocathode Electron Gun for an IR FEL" - D. Kehne

"Optical Modeling of the Jefferson Laboratory IR Demo FEL" - S. Benson

"Real-Time Transverse Emittance and Phase-Space Monitor" - J. Song

Accelerator Systems

Regarding the beam-transport system:

All optical chicane dipoles are now in house and in-coming mechanical inspections and Hall probe measurements have been completed. As noted on last week's reports, these magnets have not met specifications. We are planning to improve the assembly procedure in-house and re-measure these magnets.

We have sent a Jefferson Lab staff member to the vendor (Everson Electric) for several of the dipole magnets to review assembly procedures.

The RF shielded bellows was successfully redesigned, fabricated, and leak tested. The radiation shielding for the tune-up, recirculation, and straight ahead dumps was reviewed and it was decided that the usage of existing SEG blocks and some lead bricks would satisfy our needs.

The drawings for the magnet stands in the recirculation line are complete and await signature. One differential pumping station was assembled this week and ready for installation.

Regarding cryomodule fabrication:

The cryounit remains stable at 2k. Plans are in place for cool-down of the full cryomodule on Aug. 24-25. Commissioning will start when associated RF systems are complete.

Regarding RF systems:

Both 50 kW klystron systems are now in the FEL building. The installation for the quarter cryomodule is about 40 % complete. Both 225 kW variable power supplies from Hipotronics have been installed. The first unit has been connected to AC power. Its installation is just getting started. The second unit is for an upgrade next year. Minor repairs need to be made to both units as a result of shipping damage. The RF system for the linac is about 40 % complete. We are still waiting for direction from the vendor on what they want us to do with the second failed spare 50 kW klystron. The buncher water skid is ready for installation. The RF system for the buncher is about 40 % complete. The Master Oscillator (M.O.) and its components are installed in the FEL building. Insulation of the LCW pipe and M.O. distribution cables are to be finished this month. The M.O. system is about 80 % complete. The elbow for the 500 kV High Voltage Power Supply was reworked and is back on site. Next week J. Fugitt will determine if it now usable.

Regarding instrumentation and control systems:

The installation activities included beam position monitor electronics and completion of cabling. The vacuum cable installation was delayed due to additional cable trays being hung in the tunnel. All of the ion pump power supplies are checked out and are being installed in the racks, both crates are already in.

Beam viewers are being fitted with 1.5 micron Al foil for installation, also the multislit devices are awaiting installation.

The Personnel Safety System will be certified beginning next week.

Hardware and software debugging continued on the cryomodule temperature diodes.

The IOC's are operational, the network hub had a slight problem recovering after a scheduled power outage, this was quickly rectified. The servers FEL1 and 2 are running fine.

The Analog Monitoring System (AMS) system prototype boards are working well, the system is running with flat response out to 10MHz. The design should be finalized by this week with production PCB's to go out by next week. Work continues on the dump instrumentation and interlocks.

FEL Systems

Wiggler

Another clearance problem in the wiggler vacuum chamber support was found. The T-bars were then sent out to be modified. The plates for the wiggler girder were lowered by one inch and regrouted and the wiggler was reinstalled and surveyed into its final position.

Optics

The week was spent finishing up work on the optical transport pipe in the accelerator enclosure. Pipes were cut (or added) to the correct length, and flanges were welded to them. We will begin vacuum checks next week. The mirror can stand in Optics Control was shortened to the correct height, and was aligned so the transition pipe will be properly aligned to the beam. That pipe is being fabricated today (8/15). The installation crew set all of the upstairs optical transport stands to the correct height and began installation. The TJNAF machine shop modified the gimbal mounts to the correct i.d., this allowed us to complete the downstream cavity assembly. We will leak check it and then move it to the FEL building when the cable tray installation and cable move is more or less complete. The parallelism between mirrors and their mounts was checked. There is a definite improvement when the mirror is loaded during the indium brazing procedure. The residual tilt is < 1 mrad, easily corrected by the gimbal mounts.

Commissioning/Operations

The Diagnostic Integration plan was presented at the weekly commissioning meeting. The slides can be viewed on the www at: http://www.jlab.org/~legg/081297_comm/commtg.ps. The main points were:

The diagnostic integrators are responsible for the hardware.

The diagnostic integrators are responsible for the software to operate the devices.

They are not responsible for data analysis or high level applications.

High level software to execute particular test plans will require the Principal Investigator to write it or see the software group and discuss the need. They will put it in the queue for software tasks and ask the commissioning group for the FEL to assign it a priority within the FEL tasks. Similarly, the Diagnostic Review committee will rule on changes to diagnostic hardware and priorities.

It was reported that it was not possible to align the wiggler using the pulsed wire system. However, the four wiggler quads have been aligned to within 100 microns and the measurement corroborated the STI measurements on the wiggler which verified that the wiggler was undamaged magnetically in shipping. We still would like to check the alignment between the wire and the wiggler which will allow cross alignment to the quads.

There appears to be a problem with the first cavity in the cryounit's Qext. The optimum loaded Qext for 1.1 mA (first light) is different enough from the 5 mA case, which was designed for, that the RF power requirement will increase by 5 kW if the situation is not corrected using a stub tuner or waveguide iris. It was decided after discussion with members of the SRF department, that the power lost was not sufficient to necessitate redesigning the waveguide into the cavity. The second cavity in the unit was acceptable and the data on the cryomodule from the VTA had not been analyzed yet.

The results from the Injector Test Stand 350 kV tests were summarized in the paper, "Experimental Results from a DC Photocathode Electron Gun for an IR FEL", Kehne, et al., to be presented at the FEL conference in Beijing. The longitudinal measurements in the paper are noteworthy for their agreement with PARMELA.

A technical note on "Fine Phasing for the Cryomodule Using the Energy Recovery Dump" was completed after review by the Performance Integrator for RF phases for the FEL.

Facility

Punch list work continues as does site preparation for seeding. The elevator is operable under Plant Engineering control but has not been signed off. Problems with condensation dripping from chilled water lines are being addressed.

Clean Air Technology certified the clean room. The waveguide for the buncher was installed. The second 50 kW klystron and power supply were moved to the FEL facility. The final stand for the drive laser transport line was signed off.