• C. Benabderrahmane, P. Berteaud, N. Béchu, M.-E. Couprie, J.-M. Filhol, C. Herbeaux, C.A. Kitegi, J.L. Marlats, K. Tavakoli, M. Valléau, D. Zerbib
  SOLEIL, Gif-sur-Yvette

The pro­duc­tion of hard X rays at SOLEIL, a 2.75 GeV, re­quires short pe­ri­od and small gap in-vac­u­um un­du­la­tors. For shift­ing fur­ther the ra­di­a­tion to­ward high­er en­er­gies, the peak mag­net­ic field of the un­du­la­tors can be fur­ther in­creased by cool­ing the per­ma­nent mag­nets at cryo­genic tem­per­a­ture below 100 K. A R&D pro­gramme for the con­struc­tion of a 2 m long 18 mm pe­ri­od CPMU is launched: the use of PrFeB en­ables to in­crease the peak mag­net­ic field at a cryo­genic tem­per­a­ture of 77 K. Praseodymi­um was cho­sen in­stead of Neodymi­um type mag­nets, be­cause it pre­vents the ap­pear­ance of the Spin Re­ori­en­ta­tion Tran­si­tion. The mag­net­ic char­ac­ter­i­sa­tion of dif­fer­ent per­ma­nent mag­net grades at cryo­genic tem­per­a­tures (NdFeB and PrFeB), and the mag­net­ic and ther­mal mea­sure­ments on a small 4 pe­ri­od NdFeB cryo­genic un­du­la­tor are pre­sent­ed. The sta­tus on the progress of the CPMU con­cep­tion is given. The mag­net­ic and me­chan­i­cal de­sign, in­clud­ing the cool­ing of the gird­ers at 77K, and the ther­mal bud­get are de­scribed. The de­signs of the ded­i­cat­ed mag­net­ic mea­sure­ment bench­es, which will be re­quired to check the mag­net­ic per­for­mance of the un­du­la­tor at low tem­per­a­ture, are also re­port­ed.

• O. Marcouillé, P. Berteaud, P. Brunelle, N. Béchu, L. Chapuis, M.-E. Couprie, J.-M. Filhol, C. Herbeaux, A. Lestrade, J.L. Marlats, A. Mary, M. Massal, M.-H. Nguyen, K. Tavakoli, M. Valléau, J. Vétéran
  SOLEIL, Gif-sur-Yvette

The pro­duc­tion of high flux­es in the hard X-rays re­gion is a major issue on medi­um en­er­gy stor­age rings. It re­quires the in­stal­la­tion of In­ser­tion De­vices with high mag­net­ic field and a large num­ber of pe­ri­ods. The con­struc­tion of a su­per­con­duct­ing wig­gler has been first en­vis­aged but re­veals to be main­te­nance con­strain­ing, much more com­plex and ex­pen­sive than the per­ma­nent mag­net tech­nol­o­gy. A small gap in vac­u­um wig­gler com­posed of 38 pe­ri­ods of 50 mm has been pre­ferred. The com­pact mag­net­ic sys­tem al­lows to pro­duce in a lim­it­ed space a mag­net­ic field of 2.1 T in a small gap of 5.5 mm, where­as an aux­il­iary coun­ter­force sys­tem based on non-mag­net­ic springs com­pen­sate the mag­net­ic forces (up to 8.5 Tons) act­ing be­tween mag­net ar­rays. The gap be­tween jaws and the me­chan­i­cal de­for­ma­tions have been con­trolled and cor­rect­ed. Magic fin­gers cor­rec­tions have been also per­formed to re­duce the in­te­grat­ed mul­ti­poles and to min­i­mize the 2nd order in­te­grals re­sult­ing from the tight width of the wig­gler poles. This paper pre­sents the de­sign of the wig­gler, the con­struc­tion, and the re­sults of the mea­sure­ments after mag­net­ic cor­rec­tions.