1 / 9

Feasibility Check / H ow to test

Polarized 3 He ion source / Polarized 6 Li ion source. Feasibility Check / H ow to test. What should be checked experimentally and with simulation (if possible) Depolarization in the ionizer : inject polarized 3He gas supplied by (1) Polarized Target at RCNP or (2) LKB, Paris

ariane
Download Presentation

Feasibility Check / H ow to test

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. Polarized 3He ion source / Polarized 6Li ion source Feasibility Check / How to test • What should be checked experimentally and with simulation (if possible) • Depolarization in the ionizer : inject polarized 3He gas supplied by (1) Polarized Target at RCNP or (2) LKB, Paris • Ionization efficiency : inject 4He gas / detect 2+ ions • Detailed study of ionization mechanism Feasibility check experiment ECR ionizer : Ionization ~ complicated multi-step Polarized 3He atoms Polarized 3He2+ ion Polarimeter ( Polarization: Pi, Intensity: Ii ) ( Polarization: Pf, Intensity: If ) NMR • Delivered from Mainz to Sheffield in 2001 • magnetized spin box • Housing a glass vessel • Relaxation time ~ 50 hours (reproducibly ?) Theoretical / Simulation evaluation

  2. Critical field to keep polarization : B B I I F J J Critical Field to keep polarization Hyper Fine Interaction Weak magnetic field Strong magnetic field ν(MHz) Ｂｃ(Gauss) 1H 1422.6 508.2 3He+ 8669.43097.1 6Li2+ 8479.2 3029.1 ECR ion source 2.45 GHz ~ 875 Gauss 10 HGz ~ 3571 Gauss

  3. ECR Plasma Polarized 3He atoms Polarized 3He++ Ions Ionization = Multi-step Process e 1+ e 2+ 3He2+ e e Depolarization Mechanism Magnetic Field :B Ion confinement time : tconf Micro Wave 10 msec at 10 GHz (ANL) • Ionization process / Electron Capture and FI/HFI • 3He → 3He+ + e- : depolarization with HFI • 3He+ → 3He++ + e- : no depolarization • 3He++ + e- → 3He+ : depolarization with HFI • 3He++ + e- → 3He+* → 3He+ + hν : depolarization due to HF (LS coupling) • Spin Flip due to Electron Spin Resonance (ESR) and HFI • 3He+ + μ wave → ESR transition ~ electron spin flip ~ HFI : only ECR resonance zone • Others Electron Cyclotron Resonance : Electron Spin Resonance :

  4. HIPIS High vacuum ~ 5*10-6 torr Low vacuum ~ 2*10-5 torr Results on depolarization (1) : full effects Polarized 3He atoms ~ polarization : 50 % • Includes depolarization due to : • Ionization / capture process • Spin flip with ESR and HFI • Occurred any place in ECR plasma • Can be seen • High ECR frequency • ~ confinement time ~ long • ~ ionization process : many times • Low vacuum • ~ electron capture • ~ low polarization • Others Polarization ECR frequency (GHz)

  5. Micro Wave Mirror Coil Sextupole magnet electron Plasma Sextupole magnet B(Z) Cyclotron Resonance 875 Gauss 0 Z (mm) 700 What should be considered carefully • Spin flip due to ESR • ESR ~ only at ECR resonance field region ~ at B=B0=mwECR/e • RF magnetic field : B1 due to micro wave ~ randomly oriented • B1max = (2u0s/c)1/2 : s~ pointing vector for microwave RF power • B1 ~ very small • One Larmor precession of the electron in B1 : • (γJB1)-1 ~ μ sec • Time to pass Resonance zone (10 um / 105 cm/s ~ 1 ns) • Too short to flip the spin of electron • Can be neglected • 2. Confinement time ~ Depolarization in Ionization Process • 3. Polarized He gas transfer from ECR Loss Cone ~ confinement time • 4. Others

  6. Results on depolarization (2) Polarized 3He atoms ~ polarization : 50 % Remove ESR effects Include ionization process Recover polarization thanks to ESR effects neglect High ECR frequency ~ long confinement time ~ dominant process = ionization Polarization High vacuum Low vacuum ECR frequency (GHz)

  7. Results on depolarization (3) Polarized 3He atoms ~ polarization : 50 % • Comparison • Confinement time ~ 1 msec : blue • Confinement time ~ 10 msec : red • Without ESR effects • High vacuum • Possible to realize high polarization • with reduction of confinement time • by the adjustment of mirror ratio of • ECR ionizer … Polarization High vacuum Low vacuum ECR frequency (GHz)

  8. Results (3)

  9. What should be done Next • Understand the Depolarization mechanism • Consider / evaluate each depolarization process carefully • Polarization estimation obtained by existing ECR (HIPIS) • Idea to Overcome the depolarization • (1) Straightforward ~ high polarization 3He atom + short confinement time = high polarization + low intensity • (2) Nice Idea ….. ~ should be considered … • Preparation to measure the depolarization / feasibility test

More Related