MEMORANDUM

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

cc: Division (M7), FEL Coordination Group

From: F. Dylla

Subject: IRFEL Weekly Report, July 21-25, 1997

Date: July 25, 1997

Management

Technical highlights of the week include considerable progress installing injector components and peripherals in the FEL Facility, and the wiggler table was placed in position (see under "Facility" below). Assembly and initial leak checks of the cryomodule were completed as well, and the cryomodule is now scheduled to be installed in the FEL Facility on 1 Aug 97.

Programmatic highlights of the week include obtaining Navy signatures on the Memorandum of Agreement for release of the $3.7M of FY97 funds to Jefferson Lab; it completed its final signature loop in the Navy and, as of 25 Jul 97, was slated to be shipped by overnight mail to Jefferson Lab's Department of Energy site office. However, prospects for additional near-term funds from the Navy evaporated this week with the mark-up of the Defense Appropriations Bill in the House. No additional funds will be included for the Project in the FY98 appropriations.

The June 1997 Monthly Report for the IR Demo Project was completed and sent to the Navy Program Office and Department of Energy on Monday, 21 July.

Pre-proposals that were submitted to Jefferson Lab for initial use of the IR FEL were under review this week by an internal committee and a subcommittee of Laser Processing Consortium members. Shanti Nair (U-Mass) and Henry Helvajian (Aerospace Corp) visited the Laboratory this week to discuss the development of proposals that support the metals and micromachining applications, respectively.

Jefferson Lab was invited to co-sponsor a Workshop on Scientific Applications of 4th Generation Light Sources that will be held on 28-29 Oct 97 at Argonne National Laboratory.

Accelerator Systems

Regarding the beam-transport system:

Work is nearly complete on the modifications to the magnet measurement apparatus that will permit achieving 1 part in 10,000 resolution between members of a magnet family. Substantial progress was made on the design of the apparatus to measure the 180-degree dipoles, with most of the concept taking form.

Everson Electric glued all seven remaining cores for the optical-chicane dipoles (DWs) and are working on their assembly. They will ship two magnets early next week and the remainder the week following. They are also working on tooling for assembling the injection/extraction dipoles (DUs and DVs) and reverse-bend dipoles (DXs and DZs), which is their follow-on activity.

Process Equipment Co. pinned all of the cores of the reverse-bend dipoles and are now machining the fiducial points in anticipation of shipment late next week. The pole tips for the 180-degree dipoles are complete; the pacing item is the back legs which are being ground to their exact size by another vendor. The first coil for the 180-degree dipoles is being bent into its saddle form.

Manufacture of the Panofsky trim quadrupole continued at Magnet Enterprises International. All eight sextupole cores were received from Process Equipment Co. The schedule for the three quadrupoles for the recirculation dump line slipped at New England Technicoil to 30 Jul 97.

Regarding corrector magnets, the bids for phasing dipoles as well as the cores for the other mu- metal correctors are due early next week. Detail drawings of the coils for the two 8-inch mu-metal correctors neared sign-off. The design of the horizontal coil for the constant-perimeter air-core corrector was set back as interferences with other parts of the accelerator surfaced at many locations. At week's end, the only workable solution is to remove one of the brackets at one end of the beam-position monitors, on which these correctors are to be mounted. A formal Change Request will be submitted to flush out any objections. The configuration of the vertical corrector nesting coil set still needs to be generated. Next week we plan to prototype the horizontal corrector and test for cross-talk with a quadrupole placed nearby, as would be the case in the transport lattice.

Welding of the bodies for the optical-chicane vacuum chambers is complete. Our Machine Shop is working on the end parts, aiming for completion next week. The X and Y chambers are now complete. The first batch of parts for welding the reverse-bend chambers arrived with the final batch due on 12 Aug 97. The Shop will not be lacking parts to keep the welding effort working smoothly and on time. Two lengths of vacuum pipe remain to be detailed, one in the recirculation dump line and one on the quad telescope after the second arc. Vacuum electronics are progressing on schedule.

The last stands required are the insertable dump stand and the stands necessary for the dump lines and the quadrupole telescope located after the second arc. They are all nearing completion. Arc dipole stands are now contracted and are due 15 Aug 97. Contrary to an earlier report, the design of the sextupole/trim-quad girder is still in process.

Regarding magnet power supplies, most of the associated cables for the power supplies for the recirculation and injection/extraction dipoles was pulled. Progress is also being made on the rotating-coil probes that will be used to zero the dipoles at the dump switch points.

Regarding cryomodule fabrication:

Cryomodule assembly is now complete, and preliminary leak checks are also complete. Cleanup and full qualification of helium circuits and the insulating vacuum space is underway. Installation of the cryomodule in the FEL Facility is scheduled for 1 Aug 97.

Regarding rf systems:

Acceptance tests of the first-unit cathode power supply were conducted at the vendor, Hypotronics, with oversight from a Jefferson Lab staff member. The unit will enable powering the cryomodule's klystrons to 8 kW. Tests were sufficiently successful to merit shipment of the unit to Jefferson Lab. It is slated to be received next week. There are some relatively minor technical adjustments that we will need to make once it is received.

The second 50 kW klystron system for the cryounit is slated to be moved from the Injector Test Stand to the FEL Facility on 6 Aug 97. It had been left at the ITS to permit testing of ceramic rf windows. Once moved to the Facility, it will again be configured to permit testing windows there.

Regarding electron-beam instrumentation and controls (I&C):

Cabling and terminations for the clean room in the FEL Facility are complete, and the photocathode drive laser can now be operated through the same server that was used in the Injector Test Stand.

Assembly of the charge-coupled-device cameras for the electron-beam viewers has started, and interconnections for the beam-viewer solenoids are being worked.

Both hardware and software for the temperature diodes used to instrument the cryounit and cryomodule are progressing. The cryomodule is slated to be cooled down around 10 Aug 97, so the diodes must be accessible to the EPICS control system by that date. Software requirements for the magnet power supplies is also progressing.

Most of this week's design effort was on the analog monitoring system (which is discussed in some detail in the Commissioning/Operations section below). The initial design for the front-end buffer boards is complete and will be prototyped next week. The backplane design uses previous work done for the beam-position monitors in CEBAF's Hall B with only a minor modification.

FEL Systems

Wiggler

Arrangements were completed to get the wiggler measured via pulsed wire by Northrop Grumman in August. All parts for the wiggler viewers are ordered. Boresighting and final precision alignment of the wiggler was completed, and the wiggler is now being installed on the beamline.

Optics

Having hung the mirror cans for the optical-transport system in the accelerator enclosure, we are now doing the fine alignment. In the process, we found that some stands required modification. This was done, and we now have two (out of five) cans aligned. We anticipate doing two more today (25 Jul 97). We discovered the mirror can for the optical control room was not built correctly, and it was returned to the vendor.

We have been running tests on the accuracy of the linear variable differential transformers (LVDTs) on the gimbal mounts. Unlike the linear stage, the gimbal-mount transport seems to have negligible backlash, as reported earlier. However, we are seeing hysteresis in the LVDT readings. The problem may be in the way the LVDT was mounted; tests continue.

We received the new style picomotor controller, and it's initial checkout shows that it is quite nice. We will use it for both the drive laser optical transport and the FEL optical transport. The bellows assemblies for the optical cavity assemblies were cleaned and baked as part of their processing for high vacuum. We received part of the optical transport mirror order, as well as the collimator mirror.

Commissioning/Operations

The design and operating strategy for the FEL analog monitoring system (AMS) is finalized. The AMS will use eight 16x16 crosspoint switches manufactured by Analog Devices to accept input from 128 lines and generate output to 16 lines. The switches have built-in BNC connectors and software to allow PC control that is easily adaptable to the Lab's EPICS control system. All channels will have a root-mean-square convertor on them with a signal into EPICS, thereby allowing any of the 128 signals to be archived. The bandwidth of the AMS is limited to 1 MHz in the Machine Control Center by the fiber-optic link to the FEL Facility, but in the Facility itself the bandwidth will exceed 5 MHz. The drawback is that it has no positive verification of the channel selected; however, there is a calibration signal and the hardware is commercial, so reliability should be better. Extensive testing of the system is planned.

A question arose about alignment sensitivity of the quadrupole magnets on the injection line. During acceptance tests, these magnets are aligned by their tooling balls which are mounted to the support core. The coils are not tightly toleranced to the core, and the tooling balls themselves are not tightly toleranced with respect to each other. The result is a substantial variation, up to 1 mm, among the magnets of the location of their magnetic centers with respect to the tooling balls. In turn, the magnetic centers, while known very accurately with respect to the measurement probe used, are not known well with respect to the mechanical centers since the probe is not aligned with respect to the mechanical dimensions prior to measurement. When they are installed on the injection line, the magnets will be aligned according to the mechanical tooling, which means the electron beam will see the variation in the locations of the magnetic centers. By way of simulations, we are determining the sensitivity of the beam to this variation. If it must be corrected, we will probably install the magnets as they are, use the electron beam to determine the offsets in situ, and then realign the magnets on the injection line as necessary.

The first draft of a procedure for fine phasing of the cryomodule was drafted. The algorithm first determines zero crossings for improved sensitivity, and then determines crest and anti-crest to check for nonlinearities and develop some statistics.

Facility

Contractor punch-list work continues to correct a lot of little things. Major items remaining are certification of the elevator, which is held up in a dispute over conflicting code requirements with the city inspector. Operation will commence when the second major item remaining occurs: validation of the fire alarm system scheduled for 1 Aug 97. The HVAC chilled water system was cleared out and rust inhibitor was put in.

Meanwhile, accelerator components are being installed. The wiggler got its survey completed with quads, and the table was placed in position. Optical-transport mirror cans were mounted on the ceiling and leveled. Measurements are underway to get the intervening pipe lengths cut to the proper length so that vacuum hookup can occur. About 90% of the high-current magnet cables were mounted in the cable trays. Work continued apace to bring the rf supplies into operation on schedule. Signal hookups to the clean room were completed in preparation for full reassembly of the drive laser. It is now talking on the network. Electricians are about 80% through their hookup list, so almost everything that needs power has it.

The injector light box was aligned and connected to the photocathode gun.

The buncher cavity has been set in position. We are close to being able to complete the rest of the beamline to the cryounit. The gun's high voltage power supply is nearing readiness for an air test at reduced voltage. The cryounit continues to be at 2K with 65% liquid level. The system is stable, and preliminary investigation shows it is operating below the heat-load budget.

The drive laser was operated this week to check out the interfacing. We are also flushing the laser's chiller loop to clear it of bacterial contamination. There are HVAC issues still outstanding, but we believe we can lower the humidity by operating a dehumidifier in the room. Design is complete for all but two of the stands for the optical transport of the drive-laser beam to the photocathode. The remaining vacuum components for the drive line were ordered.