Major radius of the toroids, m. 1.46. Bending magnetic field, G. 1.75-124. Gradient of the quadrupole magnetic field, G/cm. 5-10. Electron beam radius, cm. 1.5.
MODIFIED BETATRON PROTOTYPE DEDICATED T O ELECTRON COOLING W I T H CIRCULATING ELECTRON B E A M M.Chelnokov, S.Fedorenko, V.Kalinichenko, Yu.Korotaev, I.Meshkov, S.Mironov, A.Petrov, I.Sedykh, A.Smirnov, A.Sidorin, E. Syresin, I.Titkova, G.Trubnikov,JINR,Dubna.Russia Table 1. Generalpaarametersof the Modified Betatron Prototype. Ring parameters The electron cooling system with circulating 18.28 Circumference, m electron beam based on the modified betatron was 1000 Longitudinal magneticfield,G proposed in [1,2] as a possible way to avoid the problems of a traditional cooling system at medium electron Major radius of the toroids, m 1.46 energy. Main peculiarities of this system are the Bending magneticfield,G 1.75-124 following: the use of the longitudinal magneticfieldfor Gradient of the quadrupole 5-10 an intense electron beam focusing and spiral quadrupole magneticfield,G/cm coils to provide the long term stability of the drift motion 1.5 Electron beam radius, cm of the electron beam, induction acceleration of the Residual gas pressure, Ton 10-10 electrons. In order to test such a system, its prototype Electron beam parameters called Modified Betatron Prototype (MOBY) was At injection After designed at the JINR and is under construction now. The acceleration main goal of the M O B Y creation is to study the particle 10 4360 motion dynamics, including electron injection and Energy, keV Current, A 0.02 0.1 extraction, induction acceleration of the beam and its 300 Revolution period, nsec 60 stability. Acceleration cycle The main limitations of the electron cooling 50 Induction voltage amplitude, V system based on the modified betatron are discussed. The 1 Repetition frequency, Hz general parameters of the M O B Y are presented. Cycle duration, msec 10
Abstract
1 INTRODUCTION
2 G E N E R A L LIMITATIONS As a part of the Tevatron luminosity upgrade program a new ring called "The Recycler" is being The lower limit of the focusing longitudinal constructed at the Fermilab. Electron cooling of the 8 magneticfieldin the electron ring is determined by two GeV antiprotons in thisringcould permit faster stackingconditions: the electron drift velocity (in the crossed rates and larger antiproton stacks. The electron cooling fields of the electron beam and the solenoid) is to be system with a circulating electron beam can be used for smaller than the electron thermovelocity and Larmor this aim. In this case the Recycler ring is to be equipped radius of the electron transverse motion is to be smaller of with an additional electron one, which is periodically the distance between electrons - so called condition of the filled up with new portion of cold electrons. The electron magnetisation [4,5].For Recycler cooling system, acceleration of the electron beam can be provided in the where the electron temperature is to be of Te ~ 0.2 eV, same ring using induction acceleration of electrons or these conditions are very modest: at electron current of 2 electron beam at required energy is injected from A the magneticfieldvalue has to be higher than 200G. additional accelerator. The investigations of the evolutionHowever, to prevent a heating of the electron beam by the of electron beam parameters during circulation and test a field distortions at junctions of solenoids of different possibility to use the induction acceleration of electrons geometry (straight and toroidal) so-called adiabatic are planed with the M O B Y (Fig.1). Its general condition is to be satisfied: 2πρ
