PANDA Collaboration Meeting March 03, 2008 Proposal of an Original Double RF-Funnel Technique for setups of high density gas stopping cells Victor L. Varentsov ITEP / FAIR victor.varentsov@fair-center.eu Darmstadt, July-August, 2016 Victor Varentsov

Introduction Here I propose an original Double RF-Funnel technique that can be used for high density gas stopping cells for effective ion beam extraction, cooling and bunching. The operation of this technique I have explored by means of detailed gas dynamic and ion-trajectory Monte-Carlo simulations, which are similar to the simulations described in details e.g. in my work Ref.: V. L. Varentsov, Focused ion beam source of a new type for micro- and nanoelectronic technologies, Proc. SPIE 7025 (2008) 702509-12. doi:10.1117/12.802356 By means of these computer experiments I investigated ion beam extraction from two following He gas stopping cells: Room temperature gas cell at Po = 1 bar and To = 300 K Cryogenic gas cell at Po = 0.3 bar and To = 70 K The design and operation parameters of the double RF-funnel are the same for the both these gas cell cases. Schematic view of the double RF-funnel design combined with results of gas dynamic simulations for helium gas velocity flow field are shown in the next 2 slides. Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Schematic view and Gas dynamic simulation Room temperature gas cell Po = 1 Bar To = 300 K Gas Velocity flow field Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Schematic view and Gas dynamic simulation Cryogenic gas cell Po = 0.3 Bar To = 70 K Gas Velocity flow field Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Main design parameters Nozzles 1st 2nd Half-angle of converging cone 26.5o _ Half-angle of diverging cone 45.0o Throat diameter 0.3 mm 0.8 mm Exit diameter 2.0 mm Funnels 1st RF-only 2nd RF+DC Entrance aperture diameter 8 mm 2 mm Exit aperture diameter 0.8 mm Electrode thickness 0.1 mm 0.2 mm Inter-electrode spacing 0.25 mm 0.5 mm Number of electrodes 144 25 1st nozzle – 1st funnel distance 10 mm - 2nd funnel – extraction lens distance Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Main operation conditions Parameter Room temperature gas cell Chamber Gas cell 1st funnel 2nd funnel He gas pressure 1 bar 3.0 mbar 3.3 ∙10-4 mbar Gas fow rate through chamber [mbar l/s] 32.2 31.87 0.33 Required pumping speed [l/s] - 10,6 1000 Parameter Cryogenic gas cell Chamber Gas cell 1st funnel 2nd funnel He gas pressure 0,3 bar 0.6 mbar 2.4 ∙10-4 mbar Gas fow rate through chamber [mbar l/s] 19.8 19.56 0.24 Required pumping speed [l/s] - 32,6 1000 Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Continuous ion beam operation Operation parameters Funnel 1st RF-only 2nd RF+ DC RF-amplitude [Vpp] 10 100 RF-frequency [MHz] 5 nozzle – funnel DC bias - - 0.7 V DC potential gradient - 0.21 V Extraction potential applied to the exit funnel electrode - 15.0 V Extraction lens potential - 50 V The both nozzles are grounded Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Monte Carlo ion trajectory simulations Time of Flight spectrums of continuous beam for ions M = 100 Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Monte Carlo ion trajectory simulations Axial velocity distributions of continuous beam for ions M = 100 Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Monte Carlo ion trajectory simulations Radial velocity distributions of continuous beam for ions M = 100 Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Monte Carlo ion trajectory simulations Cumulative radial distributions of continuous beam for ions M = 100 Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Bunched ion beam operation Operation parameters Funnel 1st RF-only 2nd RF+ DC RF-amplitude [Vpp] 10 100 RF-frequency [MHz] 5 nozzle – funnel DC bias - - 0.7 V DC potential gradient - 0.21 V Extraction potential applied to the exit funnel electrode - 15.0 V Capture potential applied to the exit funnell electrode + 10.0 V Extraction lens potential - 50 V The both nozzles are grounded Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Bunched ion beam operation Captured ion bunch geometry Distance to the 2nd funnel exit 2 mm Diameter 0.7 mm Length 0.8 mm Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Monte Carlo ion trajectory simulations Bunch extraction time spectrums for ions M = 100 Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Monte Carlo ion trajectory simulations Extracted bunch axial velocity distributions for ions M = 100 Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Monte Carlo ion trajectory simulations Extracted bunch radial velocity distributions for ions M = 100 Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Monte Carlo ion trajectory simulations Cumulative radial distributions of extracted bunch for ions M = 100 Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Parameters of extracted continuous beam for ions M = 100 Number of calculated ions = 25 000 Gas stopping cell case 1 bar, 300 K 0.3 bar, 70 K Total transmission efficiency (96.0 ± 1.3)% (99.1 ± 1.3)% Longitudinal velocity V═ (m/c) energy (eV) 9510 45.6 9550 45.2 Longitudinal velocity spread ∆V═ (m/c) energy sprerad (meV) 450 101.3 Radial velocity V┴ (m/c) energy E┴ (meV) 330 54.5 270 36.5 Radial velocity spread ∆V┴ (m/c) 550 151.3 440 96.8 Beam radius (90%) 1.08 0.66 Transverse emittance εx,y (π∙mm∙mrad) 26.5 13.2 Normalized transverse emittance εNx,y = εx,y∙[E═ ]1/2 (π∙mm∙mrad ∙[eV]1/2) 178,2 89,1 Darmstadt, July-August, 2016 Victor Varentsov

PANDA Collaboration Meeting March 03, 2008 Double RF-funnel technique Parameters of extracted bunch for ions M = 100 Number of calculated ions = 50 000 Gas stopping cell case 1 bar, 300 K 0.3 bar, 70 K Longitudinal velocity V═ (m/c) energy (eV) 9180 42.1 9100 41,4 Longitudinal velocity spread ∆V═ (m/c) energy sprerad (meV) 360 64,8 Radial velocity V┴ (m/c) energy E┴ (meV) 200 20 Radial velocity spread ∆V┴ (m/c) 250 31.3 Beam radius (90%) 0.61 Transverse emittance εx,y (π∙mm∙mrad) 9.5 9.4 Normalized transverse emittance εNx,y = εx,y∙[E═ ]1/2 (π∙mm∙mrad ∙[eV]1/2) 61 Darmstadt, July-August, 2016 Victor Varentsov

Conclusion I have many reasons to believe that proposed Double RF-funnel Technique will find application in many present and future gas stopping cell setups for ion beam extraction, cooling and bunching. 2. Please, feel free contact me for collaboration. Darmstadt, July-August, 2016 Victor Varentsov