ZGOUBI USERS' GUIDE - HEP

118 4 DESCRIPTION OF THE AVAILABLE PROCEDURES˜@˜@ à O þÿ)@¾¾> Ž O ¿ >4 1@¡)U¾¾¦UNIPOT: Unipotential cylindrical electrostatic lensThe lens is cylindrically symmetric about § the -axis.The length of the first (resp. second, third) § q electrode §is 4 (resp.The ˜ q potentials ˜ are and . The inner radius is 1is [27]§ , ). The distance between the electrodes O is .(Fig. 38). The model for the electrostatic potential along the axisO ¿¤£¥¤ é ÃÄn&`é Ã> wÄ w Ž >@ w1 4Äm ˜ q> Ž¿ >Ä w Ž >& é ÃÄ›&`é Ã> ¿( distance from the center of the central electrode; = 1,318; cosh = hyperbolic cosine), from which the field¢ Ä and its derivatives are deduced following the procedure described in section 1.5.2. à §#"kS"eUse PARTICUL prior to UNIPOT, for the definition of particle mass and charge.1 41 4ÿ ¢¡The total length of the lens § q isterminates at exit of the third one. §@ §U O ; stepwise integration starts at entrance of the first electrode andFigure 38: Three-electrode cylindrical unipotential lens.