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

cc: Division (M7), FEL Coordination Group

From: F. Dylla

Subject: IR Demo Project Weekly Report, April 20 - 24, 1998

Date: April 24, 1998

FEL Management

This week involved a full week of commissioning activities with a scheduled maintenace shift on Tuesday, April 21. Highlights for the week included some additional running at mA levels to look at cathode lifetime issues, and continued check-out of electron beam diagnostics to quantify the beam quality. We got our first look at some of the beam parameters after the injector (emittance, bunch length, energy spread). The first values are within factors of 2-3 of the desired values, which is not bad for our first measurements in a non-optimized system. (See Commissioning Report below for details.)

The March 1998 Monthly Reports for the project were distributed to the DOE and Navy Program Offices on Wednesday April 22.

On Tuesday, April 21, the new acting Head of DOE's Office of Nuclear Physics, Dr. Dennis Kovar, and Sherman Fivozinski, the Jefferson Lab Contract Monitor for DOE-NP visited the Lab for a general briefing that included a tour of the FEL Facility



Installation Activities

The MPS was updated this week to include the magnet to send the beam to the 0G dump or the cryomodule. The 2F06 and 2G00 BLM‚s were mapped. The 0G01 BLM is functional, but not yet mapped.

The 180° Bend Magnet (DY) is in the final set of measurements. All earlier measurements looked fine. The first article DG corrector has been received and measured to be within its specifications.

A possible solution for the problem with the Drive Laser Pulse Controller will be tested this weekend.

The first FEL Mirror Cassette is at assembly. The FEL pipe is aligned in the Laser Control room and fiducials are established for the User Labs. Control cabling for the Laser Control room is in progress.

The ND2 filter for the Drive Laser was placed under EPICS control.

The installation of a CARM for the Wiggler area is in progress.



Commissioning

This week was devoted principally to measurements of beam quality, as well as improving the injector setup, but it also included a few cw runs up to mA-level average current at 38 MeV energy to the straight-ahead dump. We are generally measuring six-dimensional phase-space parameters of the beam that are within factors of 2-3 of theoretical, a favorable situation given that we just turned on the machine. It means there are no apparent show-stoppers to lasing, but fine tuning is needed beforehand. Specific measurements performed this week include rms normalized transverse emittance at the cryounit exit (7-8 mm-mrad vs. 3.5 mm-mrad from PARMELA), rms bunch length at the center of the cryomodule (about 2 ps, vs. 1 ps desired at the wiggler), rms energy spread at the center of the first optical chicane (0.5% vs. 0.15% desired at the wiggler), and a rough sense that the emittance at the wiggler is not too far from the 9 mm-mrad desired in that most of the electron beam can be threaded through the mm- size holes in the three wiggler viewers. Getting a sufficient array of beam diagnostics working and using them to configure the quality of the electron beam at the wiggler location are now our highest-priority tasks. They will occupy the bulk of our commissioning time in the next two weeks, in which will be interspersed some cw runs at high average current to exercise the machine and get more data on cathode lifetime.