1. Machine Advisory Committee for NICA 19-20 October 2015 MPD SPD Transfer channels Options of HV Electron Cooling System for NICA Collider I.Meshkov for NICA Team JINR, Dubna HV E-Cooler 1

2. 1 st concept of the HV e-cooler Two beams or not… 1. Evident scheme – two beams (IM, 2008) HV generator e-gun e-collector e-gun 2. More sophisticated scheme (VP, 2011) – one (common) electron beam HV generator e-gun e-collector The solution is technically good, however the electron beam is a feed back between two ion beams: an instability in one ion beam excites electron beam that brings the instability signal to another ion beam, i.e. we have “the three beams’ instability”! Finally the scheme with common electron beam has been rejected. I.Meshkov NICA HV E-Cooler NICA MAC 19 October 2015 2

3. The solenoids in both concepts are supposed to be superconducting Warm solenoids in JINR version (4 copper layers winding): P total  500 kW I.Meshkov NICA HV E-Cooler NICA MAC 19 October 2015 9 m 10 m 7.0 m 6 m 1.5 m JINR Budker INP Two Present Concepts of the HV Electron Cooler with Two Electron Beams (See talk of Andrii Kobets) 3

4. I.Meshkov NICA HV E-Cooler NICA MAC 19 October 2015 gun collector 3D Design of HV Electron Cooler for COSY V.Reva, COOL’2015 electron beam proton beam Electrostatic Accelerator Cooling section

5. Three Options of the HV E-Cooler of NICA Collider I.Meshkov NICA HV E-Cooler NICA MAC 19 October 2015 5 Option 1 (See talk of Andrii Kobets) Main features: 1) 3 tanks’ scheme 2) Two opposite beams in each tank 3) Common solenoid for both acceleration tubes HV Generator: - Voltage multiplier (“Cockroft – Walton”) - Cascade transformer (BINP version) Advantage: - a short solenoid system (about twice shorter of the BINP system); - a reliable scheme of the voltage multiplier applied for HV generation. Disadvantage: - wide conic (SC?) solenoids inside the tanks - probable problems at tuning of the cooler regimes when electron beams are ON.

6. I.Meshkov NICA HV E-Cooler NICA MAC 19 October 2015 6 Three Options of the HV E-Cooler of NICA Collider Advantages: - application of the BINP experience: reliable scheme of the cascade transformers for HV generation and solenoid coils’ dc feeding. Disadvantages: - very complicated (if possible) design of individual SC solenoid coils inside the tanks; - a long solenoid system for the beam transportation outside the tanks; - the same probable problems at tuning of the cooler regimes when electron beams are ON. Option 2 Main features: 1) 2 tanks’ scheme; 2) Individual beams (back and forth) in each tank; 3) Individual (warm?) solenoids and acceleration systems for each acceleration tube; 4) HV Generator: - Cascade transformers. BINP design (for instance)

7. I.Meshkov NICA HV E-Cooler NICA MAC 19 October 2015 7 Three Options of the HV E-Cooler of NICA Collider Option 3 Main features: 1) 2 tanks’ scheme; 2) Two opposite beams in each tank; 3) Individual (warm!) solenoids and acceleration systems for each acceleration tube; 4) HV Generator: - Cascade transformers (BINP version). Advantages: - a shorter solenoid system (about twice shorter of the BINP system); - application of the BINP experience: reliable scheme of the cascade transformers for HV generation and solenoid coils’ dc feeding. Disadvantages: - very complicated (if possible) design of individual SC solenoids inside the tanks; - the same probable problems at tuning of the cooler regimes when electron beams are ON. BINP design (for instance)

8. I.Meshkov NICA HV E-Cooler COOL’2015 29 September 2015 Concluding remarks The design of the HV Electron Cooler for NICA Collider is still in the concept development stage. The final choice of the Cooler scheme can be done after more detailed analysis of the versions and R&D. Application of HTSC solenoids requires further and more active R&D. The experience of BINP e-cooler at the COSY will give many answers soon. 8 Thank you for your attention!