U.S. Particle Accelerator School

Beam Measurements course

Sponsoring University:

Old Dominion University


Beam Measurements, Manipulation and Instrumentation at an ERL FEL Driver

Steve Benson, David Douglas, Pavel Evtushenko, George Neil, and Chris Tennant, Jefferson Lab

Purpose and Audence:
The purpose of the course is to make students familiar with procedures and techniques used in beam tuning of and ERL and FEL. The course is intended to be mainly hands-on work with beam and tools used for the beam measurements and manipulation. The course is intended for graduate-level students with a good background in accelerator physics to postdocs working in the field.

USPAS undergraduate course "Fundamentals of Accelerator Physics & Technology" or equivalent experience.

It is the responsibility of the student to ensure that he or she meets the course prerequisites or has equivalent experience.

The objectives of the course are: 1) become familiar with beam instrumentation and diagnostics used at ERL including hardware and software tools, 2) learn about essential aspects of the instrumentation design and its preparation for the measurements, 3) learn most important steps of the setting up of an ERL electron beam, 4) participate in tuning electron beam of ERL and make the beam characterization, 5) perform data evaluation of the beam measurements

Instructional Method:
The main points of the course are intended to be a set of hands-on beam experiments and lab experiments with beam instrumentation. During joint morning session a brief lecture will give background and introduce essential concepts and techniques, which will be used later during the experiments conducted on that day. The students of the course will be split in to two groups. First, one of the groups will work on the lab measurements and experiments with the beam instrumentation and the second group will perform measurements and experiment with the electron beam of the IR Upgrade. Later on in the day the groups will change places. One of the goals of the course is to allow the students to become familiar with the hardware used for the beam measurements. Main aspects involved in the design of the beam instrumentation hardware will be discussed. During the lab exercises students will be able to work on the instrumentation as if it has been prepared for the beam measurements. The measurements and manipulations with the beam, which will be discussed and exercised in the course, will be a set of operations required to establish proper setup of the ERL driving the FEL. The specifics of such beam tuning of an ERL will be emphasized. During the beam setup operations beam measurements will be obtained. The evaluation of some of these data will be given as homework. When the accelerator is setup and the lasing of the FEL is obtained, a set of measurements of the FEL photon beam used the FEL characterization will be made and discussed.

Course Content:

    Lab experiments
  1. Stripline BPM and its electronics test stand
  2. Viewer/optics test stand
  3. Video acquisition test stand
  4. Beam current monitor (BCM) test lab
  5. Cavity/LLRF test stand
  6. Martin-Puplett interferometer and FTIR
  7. Wire scanner for beam profile measurements
    Beam measurements and tuning
  1. Photocathode cathode drive laser measurements
  2. Setting up injector and beam characterization in the injector
  3. Establishing longitudinal match from the injector to the FEL wiggler and from the wiggler to the energy recovery dump
  4. Setting up proper phases of the linac cavities
  5. Low level RF signals and their importance for ERL tune-up
  6. Transverse match through the machine including section of the accelerator with two beams
  7. Emittance measurements and Twiss parameters measurements
  8. Bunch length measurements in the vicinity of the wiggler and its dependence on the longitudinal match
  9. Energy spread measurements
  10. M55 measurements and its tuning
  11. BBU demonstration

Reading Requirements:
The course will follow on-line technical notes and publications from the instructors.

Credit Requirements:
Students will be evaluated based on their participation and contributions during the Lab work (40%), during the beam measurements and tuning (40%), and homework (20%).

IU/USPAS course number P571