Fabrication technology for multi megawatt peak RF absorption layer

Abstract

An RF absorber capable of stable absorption of multi MW peak and several kW average powers is needed for traveling wave mode high gradient accelerating structures. At the end of structure an RF load is used to absorb residual RF power left in the system. Typically, a liquid media (for example, pure water) is used as an effective power absorber of this residual power. However most large scale accelerators require a metal interface to separate the high RF vacuum envelope and any liquids used to carry away heat from RF absorption. This requirement comes from a desire to minimize the possibility of contaminating the vacuum envelope. The metal/liquid interface is a weak component for a high peak power mode operation. Our presentation we will address is the development of a multi MW RF absorber that is compatible with ultra-high vacuum operation while reliably and stably absorbing MW level peak power. Load prototypes developed at SLAC using this technology have proven capable of absorbing >30 MW peak, >4 kW average, and 120 Hz RF pulse with an attenuation rate 5.5 dB per meter for S-Band case.