RF gun cavities cooling regime study

At DESY normal conducting RF Gun cavities operate with electric fields at the cathode of Ec = 40MV/m or Ec = 60MV/m and a pulse input RF power of Pi ∼ 3.2MW and Pi ∼ 6.8MW , respectively. In combination with a long RF pulse of τ ∼ 1ms and 10Hz repetition rate it results in average dissipated RF power of Pa = 0.01Pi, equal to Pa ∼ 32kW and Pa ∼ 68kW . Taking into account the cavity dimensions, the average RF power of Pa ∼ 68kW corresponds to a heat load of ∼ 300 kW m . To remove such a high heat value from the cavity body, an advanced cooling circuit is required. The cooling circuit capability depends on the cooling channel design and the water flow parameters and finally defines the maximal possible dissipated RF power, which can be removed from the cavity and, hence, limiting the cavity duty factor. In this report we describe a cooling circuit study for DESY RF Gun cavities N2, N3 with the aim to optimize the water flow distributions for a maximal dissipated RF power. For Gun 4, with independent cooling channels, the goal of the study is to investigate the flexibility of such a design decision.