Hydroforming of Tesla Cavities at Desy

Conference · Sat Jul 01 04:00:00 EDT 2000

OSTI ID:839250

Singer, W; Kaiser, H; Singer, X; Gonin, I; Zhelezov, I; Khabibullin, T; Kneisel, P; Saito, K

Since several years the development of seamless niobium cavity fabrication by hydro forming is being pursued at DESY. This technique offers the possibility of lower cost of fabrication and perhaps better rf performance of the cavities because of the elimination of electron-beam welds, which in the standard fabrication technique have sometimes lead to inferior cavity performance due to defects. Several single cell 1300 MHz cavities have been formed from high purity seamless niobium tubes, which are under computer control expanded with internal pressure while simultaneously being swaged axially. The seamless tubes have been made by either back extrusion and flow forming or by spinning or deep drawing. Standard surface treatment techniques such as high temperature post purification, buffered chemical polishing (BCP), electropolishing (EP) and high pressure ultra pure water rinsing (HPR) have been applied to these cavities. The cavities exhibited high Q - values of 2 x 10{sup 10} at 2K and residual resistances as low as 3 n{Omega} after the removal of a surface layer of app. 100 {micro}m by BCP. Surprisingly, even at high gradients up to the maximum measured values of E{sub acc} {approx} 33 MV/m the Q-value did not decrease in the absence of field emission as often observed. After electropolishing of additional 100 {micro}m one of the cavities reached an accelerating gradient of E{sub acc} {ge} 42 MV/m.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (US)
• Sponsoring Organization: US Department of Energy; USDOE Office of Energy Research (ER) (US)
• DOE Contract Number: AC05-84ER40150
• OSTI ID: 839250
• Report Number(s): JLAB-ACC-00-20; DOE/ER/40150-3333
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ACCELERATORS
CAVITIES
CHEMICAL POLISHING
COMPUTERS
DATA
DEFECTS
ELECTROPOLISHING
EXTRUSION
FABRICATION
FIELD EMISSION
NIOBIUM
PERFORMANCE
PURIFICATION
Q-VALUE
REMOVAL
SURFACE TREATMENTS