Analysis of rf modes in the ANL APS vacuum chamber using computer simulation, electron beam excitation, and perturbation techniques
The APS vacuum consists of a nearly elliptical beam chamber coupled to an antechamber through a 1-cm-high, 10-cm-long pumping slot over most of the 1104 m of storage ring circumference. Nonevaporable getter (NeG) strips in the antechamber are the pumping element. The 1-cm-high slot has two functions: to provide good conductance for vacuum pumping and for transmission of the photons into the beam ports. We thought that coupling of the beam to the antechamber might occur through the slot. Since the beam fields are transverse magnetic to the beam (TM/sub z/), no coupling occurs below the TM cutoff of the slot (15 GHz for 1 cm) because no wall currents are interrupted. Also, the frequency spectrum of a rigid bunch is well below 15 GHz. Both computer calculations and measurements were done to verify that no coupling occurs. Computer calculations in the frequency domain and two-arm wire measurements with picosecond pulses were previously reported. The wire measurements confirmed that little coupling occurs between the two chambers. In addition to those earlier studies, a real-time MAFIA-T3 study in 3D was done, and a measurement of modes excited by a 38-ps, 20-MeV electron beam has been completed. These results are the primary topic of this paper. Some measurements made with a network analyzer and bead perturbation equipment will also be discussed. 8 refs., 11 figs.
- Research Organization:
- Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 6160469
- Report Number(s):
- CONF-890335-200; ON: DE89014675
- Resource Relation:
- Conference: 13. particle accelerator conference, Chicago, IL, USA, 20 Mar 1989; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ELECTROMAGNETIC FIELDS
COMPUTER CALCULATIONS
ANL
COMPUTERIZED SIMULATION
ELECTRIC FIELDS
ELECTRON BEAMS
PRESSURE VESSELS
REAL TIME SYSTEMS
RF SYSTEMS
BEAMS
CONTAINERS
LEPTON BEAMS
NATIONAL ORGANIZATIONS
PARTICLE BEAMS
SIMULATION
US AEC
US DOE
US ERDA
US ORGANIZATIONS
430200* - Particle Accelerators- Beam Dynamics
Field Calculations
& Ion Optics