U.S. Particle Accelerator School
Microwave Measurement with Lab course
Sponsoring University:
Old Dominion University
Course:
Microwave Measurement and Beam Instrumentation Laboratory
Instructors:
Stefano De Santis and Gang Huang, Lawrence Berkeley National Lab; Robert Rimmer and Tom Powers, Jefferson Lab
Purpose and Audience
Modern accelerators rely on beam manipulation using electromagnetic fields at microwave frequencies. This laboratory course introduces the student to some of the RF and microwave technology and laboratory methods for its characterization. The course consists of short lectures introducing the topics covered in the laboratory exercises. Students will spend most of their time on actual measurements.
Prerequisites
Undergraduate Electromagnetism and the USPAS course “Accelerator Fundamentals”.
It is the responsibility of the student to ensure that they meet the course prerequisites or have equivalent experience.
Objectives
Provide the student with experience in measurements of RF and microwave accelerator hardware and signals using modern equipment.
Instructional Method
This course includes a series of lectures introducing fundamental concepts of microwave theory and the lab topics during morning sessions, and extensive lab sessions to demonstrate theoretical concepts. These hand-on labs include:
(1) Spectrum Analyzer: for measurement of simple signals on a spectrum analyzer to understand resolution bandwidth, video bandwidth, dynamic range, noise, etc;
(2) Time Domain Reflectometry (TDR): measure characteristics of various connector families, transmission lines and complex loads;
(3) Beam Impedance: use the wire method to measure the beam impedance of an accelerator component;
(4) Beam Signals: utilize an arbitrary function generator to simulate beam signals from the accelerator, AM for betatron signals, FM for synchrotron signals;
(5) Pickups and kickers: measure and understand to performance of a stripline used as either a pickup or kicker;
(6) Matching: design and build a simple single stub transmission line matching circuit;
(7) RF Cavities: measure mode spectrums of a cavity, the cavity coupling, loaded and unloaded Q, the electric field distribution and R/Q of a cavity by the bead pull method.
(8) Linac structure: measure mode spectrums of coupled cavities, loaded and unloaded Q; identify and understand the coupled modes and phase advance between cavities.
(9) Use of a vector signal analyzer for measuring beam signals.
Course Content
(1) Microwave Measurements in the time and frequency domains, basics of spectrum analyzers, vector signal analyzers, and time domain reflectometers;
(2) Transmission lines, complex impedance, reflection coefficients;
(3) Microwave measurements with a Vector Network Analyzer, basics of vector network analyzers;
(4) Stripline pickups and kickers;
(5) Beam signals for Circular Accelerators, beam spectrums, power spectral density, betatron and synchrotron signals;
(6) Beam impedance and methods for measuring it.
(7) Impedance matching, basic of matching devices; and
(8) RF cavity and linac structure measurements, cavity and coupled cavity structure basics, bead pull, coupling, cavity bandwidth.
Reading Requirements
(to be provided by the USPAS) “Microwave Engineering” by David Pozar (third edition), John Wiley and Sons Publishers (2005). The course will follow our notes which will be available on-line.
Credit Requirements
Students will be evaluated based on performance in the laboratory. Instructors will be actively involved with each of the students during the course of each day and each experiment. The students will be evaluated by one on one discussions about the experiments. Students are expected to submit written lab reports and solutions to the homework assignments.
IU/USPAS course number P571