TRC R1 and R2 Briefs for ITRP

 

 

The International LC Accelerator Subgroup has requested a ~1 page update on each of the R1 and R2 items identified in the TRC.　 The update should describe the latest results as well as expected R&D before June 2004.　 The relevant R1 and R2 items are listed and this is followed by a table of proposed authors for each of the items.　 The first author in the list has primary responsibility.　 The date for these pages is January 20th, 2004.　 We should have drafts of all pages by January 15th, 2004 for a final edit.　 To accommodate this tight timescale please plan to have drafts to the co-authors by Tuesday morning January 13th.　 Please include relevant references and links to web documents.　 Figures can be included in the brief or referenced in a web link.

 

 

R1

  1. For JLC-X/NLC, the validation of the presently achieved performance (gradient and trip rates) of low group velocity structures—but with an acceptable average iris radius, dipole mode detuning and manifolds for damping—constitutes the most critical Ranking 1 R&D issue. Tests of structures with these features are foreseen in 2003.
  2. The other critical element of the rf system is the dual-moded SLED-II pulse compression system. Tests of its rf power and energy handling capability at JLC-X/NLC design levels are planned in 2003. As far as the 75 MW X-band PPM klystron is concerned, the Working Group considers the JLC-X PPM-2 klystron a proof of existence (although tested only at half the repetition rate). A similar comment can be made regarding the solid-state modulator tested at SLAC.

R2

  1. There must be a full test of the JLC-X PPM klystron at the specified repetition rate of 120 or 150 Hz.
  2. These klystrons should be tested with the NLC modulator (at full specs and including arcing tests) and form part of a linac subunit test. The latter should also comprise the dual-moded SLED-II complete system, several damped and detuned structures, installed in the accelerator environment (with temperature control, for instance), and LLRF and controls systems. The test should be made with beam. The present plan is to perform this sort of test with a full girder of structures (some of them being detuned and damped) in 2004.
  3. For all the damping ring designs, further simulation studies are needed to understand the magnitude of the electron cloud effects and to explore possible means of suppressing these effects. Experiments in existing rings are needed to test the electron cloud simulations. Possible cures for the electron cloud (including chamber coatings, superimposed magnetic fields, and gaps in the bunch pattern) need to be experimentally investigated.
  4. Further simulations of the fast ion instability are also necessary. Experiments in the ATF and other suitable rings are needed to test the predictions of these simulations.
  5. Damping ring extraction kicker stability, required at the level of <10-3, is an important issue. Continued studies including experiments with the ATF double-kicker system are needed.
  6. Finally, additional simulations of emittance correction in the damping rings are needed, including the effects listed in Section 7.2.3.2. Additional experiments in the ATF and other operating rings are needed to test the emittance correction algorithms.
  7. For all low emittance transport designs, the static tuning studies, including dynamic effects during correction, must be completed.
  8. The most critical beam instrumentation, including the intra-train luminosity monitor, must be developed, and an acceptable laser-wire profile monitor must be provided where needed in each design. A vigorous R&D program is mandatory for beam instrumentation in general; it would be appropriate for a collaborative effort between laboratories.
  9. A sufficiently detailed prototype of the main linac module (girder or cryomodule with quadrupole) must be developed to provide information about on-girder sources of vibration.
  10. A detailed evaluation of critical subsystem reliability is needed to demonstrate that adequate redundancy is provided and that the assumed failure rate of individual components has been achieved.
  11. The performance of beam based tuning procedures to align magnets and structures must be demonstrated by complete simulations, in the presence of a wide variety of errors, both in the beam and in the components.

 

 

R1 / R2 Item

Person

Date

1

Adolphsen / Toge

 

2

Tantawi / Chin

 

3

Chin / Cornuelle

 

4

Schultz / Toge

 

5

Pivi / Yokoya

 

6

Raubenheimer / Yokoya

 

7

Urakawa / Ross

 

8

Wolski / Urakawa

 

9

Tenenbaum / Kubo

 

10

Ross / Hayano

 

11

Seryi / Tauchi

 

12

Himel / Phinney

 

13

Kubo / Tenenbaum

 

Overall Edit

Phinney / Yokoya