1 / 19

LBNL 88'' cyclotron operations

LBNL 88'' cyclotron operations. Status of the 88-Inch Cyclotron High-Voltage upgrade project December 14, 2009 Ken Yoshiki Franzen. Introduction. The LBNL 88” cyclotron supports world-class research by the local low-energy nuclear scientific community LANL, LLNL, Sandia

homer
Download Presentation

LBNL 88'' cyclotron operations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. LBNL 88'' cyclotron operations Status of the 88-Inch Cyclotron High-Voltage upgrade project December 14, 2009 Ken Yoshiki Franzen

  2. Introduction • The LBNL 88” cyclotron supports world-class research by • the local low-energy nuclear scientific community • LANL, LLNL, Sandia • National Space Security community (BASE facility) • Outside companies • Recently received funding for two upgrade projects: • RF • HV • Common goal: Increase reliability and efficiency! 2

  3. HV upgrade background • Space-charge effects limit transport efficiency from ion sources into center of cyclotron • For some groups (e.g. BGS) intensity is crucial, for others not really... • Goal is to increase injection energy of key ion beams in the mid-range (20<A<136), in particular for 48Ca and 50Ti... • … without impacting performance for other cases. • Target injection voltage is 25 kV (if feasible up to 30 kV) which should provide user with an improvement >2.

  4. Injector System of the 88-Inch Cyclotron Electrostatic mirror • Purpose is to deflect the beam 90°. • Consists of 47° grid and electrode. • Observe spots! • Major culprit in achieving HV injection. 12 kV gnd

  5. Mirror inflector pros and cons • Pros • Versatile • Straightforward • Easy to model Cons • Needs high voltage but current one does not go up to more than ~12 kV • Grid degradation (sputtering) • Decelerating beam 5

  6. Spiral inflector (Belmont and Pabot,1966) ground -V z +V ground Nuclear Instruments and Methods in Physics Research A 456 (2001) 177}189 6

  7. Spiral inflector pros and cons • Pros • 100 % transmission. • Lower voltage → Can do HV injection. • No deceleration. • Injected beam more centered. Cons • Narrow operational range. • Difficult to model. • More difficult to manufacture. • Causes emittance growth due to fringe field effects. 7

  8. Spiral inflector main parameters ⇐Height, or the radius of curvature of the electric field. ⇐Magnetic radius which the ion orbit would have if there was no electric field. Notice that the center orbits transmitted through a spiral inflector is fixed. ⇐Tilt, where θis angle between Eu and total E vectors and 0≤b≤2. Used to shift the orbit center. ⇐ Spiral inflector design parameter. Typical values is K=1.1. 8

  9. Spiral inflector parameters (from notes by B. Laune) • 88” center region space is very limited . • A=25 mm, Rm=33 mm for Ar9+ (injection voltage 25 kV, extraction 200 MeV) → K=0.4 • Non-standard design, detailed modeling required. 9

  10. Modeling procedure (Step 1a) • Create FEM 3D model of a general spiral inflector based on an analytical single particle model.

  11. Modeling procedure (Step 1b) • Define potentials applied to all bodies and calculate electric fields in 3D. • Track beam through electric fields with a superimposed magnetic field.

  12. Modeling procedure (step 2a) • Create FEM 3D model of a inserts compatible with spiral inflector geometry.

  13. Modeling procedure (step 2b) • Track the beam leaving the spiral inflector through a electrostatic model of the updated cyclotron center region design with output of Step 1 as input parameters. • Observe if particles make it to second gap.

  14. Modeling procedure (step 3) • Use a code from MSU (Z3CYCLONE) to track the beam from the center region all the way out to extraction. • Calculate the performance of each design in terms of transmission and energy.

  15. Tasks and Challenges • The current inflector shaft is only 2.125'' in diameter. • How to fit everything in limited space? • What about emittance growth? • Add space-charge effect to the model. • System must be versatile enough to cover required operational range. • Might need several inflectors/inserts sets. • How long time to swap inflector/insert set-up? • Reproducibility between swaps? • Important: Experimentally verify cyclotron modeling as early as possible in the design chain. 15

  16. Diagnostics • Designed a wire probe which will be used to diagnose beam coming out of inflector. • Ready to be tested and used to confirm model of current system. • Could also be useful for present Operations. • Also planning to design a scintillator probe giving additional beam diagnostics data. Spiral inflector output beam r

  17. Matching of beam lines to the upgraded cyclotron • Need to redesign buncher. • Need to redesign solenoid magnets of the injector line. • Redesign 72 degree bend magnet and assess bend capability of the existing beam lines. • Upgrade HV insulation of the ion sources. • What additional diagnostics do we need? 17

  18. Project Schedule

  19. Conclusion • HV upgrade project is on track • Many remaining issues to be resolved • Initial Operation targeted for early 2012

More Related