• Q. Wu, I. Ben-Zvi, X. Chang, J. Skarita
  BNL, Upton, Long Island, New York

The pro­posed elec­tron ion col­lid­er, eRHIC, re­quires large av­er­age po­lar­ized elec­tron cur­rent of 50mA, which is more than 20 times high­er than the pre­sent ex­per­i­ment re­sults of sin­gle po­lar­iza­tion source, such as GaAs. To achieve the cur­rent re­quire­ment of eRHIC, we have de­signed the mul­ti-cath­ode DC elec­tron gun for in­jec­tion. 24 GaAs cath­odes will be pre­pared and emit elec­trons at the ar­ranged pat­tern. De­spite of ul­tra-high vac­u­um and pre­cise tim­ing, mul­ti-cath­ode DC elec­tron gun has high de­mand on the elec­tric field sym­me­try, mag­net­ic field shield­ing, and arc­ing pre­ven­tion. In the paper, we pre­sent the 3D sim­u­la­tion re­sults of the lat­est model for the mul­ti-cath­ode DC elec­tron gun. The re­sults will give guid­ance to the ac­tu­al de­sign in the fu­ture.

• W. Guo, S.L. Kramer, S. Krinsky, B. Nash, J. Skarita, F.J. Willeke
  BNL, Upton, Long Island, New York

NSLS-II is a third-gen­er­a­tion light source that is being built at the Brookhaven Na­tion­al Lab­o­ra­to­ry. The stor­age ring has 30 dou­ble-bend-achro­mat­ic cells. Six 3.5-m-long damp­ing wig­glers (DW) will be in­stalled in three straight sec­tion to lower the emit­tance. The civil con­struc­tion of the fa­cil­i­ty start­ed in June 2009 and major ac­cel­er­a­tor com­po­nents, such as mag­nets and vac­u­um cham­bers, have en­tered pro­duc­tion phase. This paper will sum­ma­rize the physics con­sid­er­a­tions for the NSLS-II mag­net spec­i­fi­ca­tions. In par­tic­u­lar, we dis­cuss the tun­ing range re­quired by the lat­tice flex­i­bil­i­ty, and the is­sues which lead to the spec­i­fi­ca­tion for the high­er-or­der mul­ti­poles.