Computational support for ITS and PHERMEX. Final report
- Mission Research Corp., Albuquerque, NM (United States)
- Los Alamos National Lab., NM (United States)
This report describes calculations carried out over the past year in support of the ITS and PHERMEX radiographic machines. The forces produced by nonaxisymmetric structures in the ITS linac were calculated using 3-D simulations. The quadrupole magnetic field produced by the drive rods in the accelerating cell was obtained. This force can be corrected by a weak static magnetic quadrupole provided the current in the drive rods is constant. The octopole force produced by a 4-hole diagnostic section was also obtained. A new recessed cathode design was modeled using PBGUNS. For a 2 mm recess, the electrostatic focusing due to the recess is sufficient to stop current loss on the anode. The emitted and transported currents are in good agreement with the measured values. The LAMDA code was compared in detail to the LLNL code BREAKUP. The codes are in close agreement. To get the results to overlay identically, however, the beam voltages have to differ by about 100 kV (out of 3 MV). The source of this discrepancy has not yet been identified. A plotting utility for LAMDA was written in the IDL{reg_sign} language. This allows LAMDA output to be viewed on any platform supported by IDL. Experiments on the flat-cathode injector were modeled. Beam radius as a function of magnet strength was compared in detail with measurements, and good agreement was obtained. The effect of the trim coil on reducing beam emittance was investigated further. The trim coil allows one to correct emittance growth due to spherical aberration in the focusing magnet and nonlinear self forces. The measured calibrations for the bucking, focus and trim coils are now in good agreement with the calculated values. A code which optimizes the transport magnet settings was developed. The code iterates on the magnet settings to obtain a beam envelope with some user-specified properties. This procedure may be useful in tuning the ITS or DARHT linacs.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mission Research Corp., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 105850
- Report Number(s):
- LA-SUB-95-102; MRC/ABQ-R-1686; ON: DE95016318
- Resource Relation:
- Other Information: PBD: Mar 1994
- Country of Publication:
- United States
- Language:
- English
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