Squeeze%20optics%20and%20power%20converter%20settings

1
Squeeze optics and power converter settings

• S. Fartoukh, M. Giovannozzi, J. Jowett, Y.
  Papaphilippou

• Questions addressed
• Can we ramp at constant optics and crossing
  scheme?
• Behaviour of optical parameters during squeeze of
  IR1 and/or IR5
• Number of matched optics during squeeze
• Status of squeeze optics for IR2 and 8

2
Introduction

• The material concerning the squeeze for IR1 and 5
  can be found at
• S. Fartoukh -gt 23 LTC meeting, 31/03/04.
• The material concerning the crossing scheme for
  IR1 and 5 during the squeeze can be found at
• S. Fartoukh -gt LOC meeting, 11/10/05.
• All the optics files are stored in the official
  database under V6.5

3
Can we ramp at constant optics and crossing
scheme? - I

• IR1 and 5
• Optics injection optics can be ramped up to 7
  TeV
• Crossing scheme
• for beta 11 m, a 200 mrad, par. sep. 2 mm,
  MCBYs at Q4 (mainly for par. Sep.) are at 107 of
  nominal at 7 TeV -gt the injection crossing scheme
  can be ramped (tight, but feasible).
• For beta 17 m , a 160 mrad, par. sep. 2.5
  mm, the same correctors are at 132 of nominal at
  7 TeV -gt the injection crossing scheme has to be
  changed at about 5 TeV.

4
Can we ramp at constant optics and crossing
scheme? - II

• IR2 and 8
• Optics injection optics can be ramped up to
  7TeV. Important point strength of triplets is
  220 T/m instead of 205 T/m (due to the injection
  contraints of phase advance between septum and
  kicker)!
• Crossing scheme
• IR2 the MCBY correctors in Q4 are limited in
  strength. In principle the injection crossing
  scheme cannot be ramped up to 7TeV. This issue
  should be studied in more details to assess
  whether alternative solution is possible
• IR8 no strength limitation is present, even
  though the strengh requirements for MCBYs at Q4
  are tight (due to par. sep.). Injection crossing
  scheme can be ramped up to 7TeV.

5
Behaviour of optical parameters during squeeze of
IR1 and/or IR5 - I

• Status of squeeze optics
• 12 matched optics for various beta are
  available.
• Solutions provide smooth variation of the
  quadrupole gradients during squeeze.
• A crossing scheme is implemented for each of the
  matched optics.
• Criteria imposed on crossing scheme during
  squeeze
• Parallel separation kept constant
• Scaling of the X-angles
• Scaling law for the IP shift

S. Fartoukh LOC meeting, 11/10/2005
6
Squeeze (3/4)
S. Fartoukh, 23 LTC meeting
Quadrupole gradients T/m in the Dispersion
Suppressor (Q7-Q10) as a function of b beam1
(left) beam2 (right)
? Rather smooth except for 1 m ltb lt 2 m
7
Squeeze (4/4)
S. Fartoukh, 23 LTC meeting
Quadrupole gradient T/m in the trim
quadrupoles (QTL11,-QT12,QT13) as a function of
b beam1 (left) beam2 (right)

• Smooth/monotonous for beam1 but more erratic
  for beam2, with unavoidable zero-crossing for
  both beams (matching procedure could be optimised
  if needed)

8
Behaviour of optical parameters during squeeze of
IR1 and/or IR5 - III
S. Fartoukh LOC meeting, 11/10/2005
9
Behaviour of optical parameters during squeeze of
IR1 and/or IR5 - IV

• Simulation conditions
• Plain V6.5 layout with nominal optics.
• No errors (alignment or magnetic) included.
• The 12 matched optics are used (collision tunes
  0.31/0.32, and chromaticities set to 2 with SF/SD
  circuits).
• In between two matched optics the gradients are
  obtained by linear interpolation.
• For intermediate optics relevant beam parameters
  are evaluated.

10
Behaviour of optical parameters during squeeze of
IR1 - I
11
Behaviour of optical parameters during squeeze of
IR1 - II
12
Behaviour of optical parameters during squeeze of
IR1 - III
Critical region for Beam 2 smoothing should
improve it
Beam 2 seems to be more critical than Beam 1!
However, no problem down to beta 2m.
13
Behaviour of optical parameters during squeeze of
IR1 - IV
Critical region for Beam 2 smoothing should
improve it
Beam 2 seems to be more critical than Beam 1!
However, no problem down to beta 2m.
14
Behaviour of optical parameters during squeeze of
IR1 - V
Computed outside IR1/5
15
Behaviour of optical parameters during squeeze of
IR1 - VI
Computed outside IR1/5
16
Behaviour of optical parameters during squeeze of
IR1 - VII
Critical region for Beam 2 smoothing should
improve it
Computed outside IR1/5
17
Behaviour of optical parameters during squeeze of
IR1 - VIII
Critical region for Beam 2 smoothing should
improve it
Computed outside IR1/5
18
Behaviour of optical parameters during squeeze of
IR1 - IX
No impact of the squeeze on the beam parameters
at IP.
7TeV crossing parameters. Matching with injection
crossing to be discussed.
19
Number of matched optics during squeeze - I

• Two test cases considered
• Removal of two matched optics (beta 4 m and
  2.5 m).
• Beta 4 m whenever removed the optical
  parameters remain bounded, e.g., tune variation
  below 1E-3.
• Beta 2.5 m whenever removed the optical
  parameters grow, e.g., tune variation above 4E-3.
• Academic case remove successive points below 11
  m to determine behaviour of optical parameters.

20
Number of matched optics during squeeze - II
21
Number of matched optics during squeeze - III
22
Number of matched optics during squeeze - IV
23
Behaviour of optical parameters during squeeze of
IR5

• Whenever IR5 is squeezed the results are very
  much the same as for IR1 (taking into account the
  exchange of the crossing plane) no particular
  new issue observed.

24
Behaviour of optical parameters during combined
squeeze of IR1 and 5 - I

• Larger variations of the optical parameters are
  observed. In particular
• Horizontal and vertical planes have equal
  behaviour for closed orbit leakage lt 0.1 s.
• Beam 1
• Factor 2 larger tune variations -gt DQ 3E-3
• Chromaticities almost unaffected -gt DQ 0.15
• Factor 1.5 in beta-beating -gt Db/b 1.5
• Orbit leakage almost unaffected lt 0.1 s
• Beam 2 (similar values as of Beam 1, except for 1
  m ltbeta lt 2 m)
• Factor 2 larger tune variations -gt DQ 6E-3
• Chromaticities strongly affected -gt DQ 2
• Factor 1.5 in beta-beating -gt Db/b 10-15
• Orbit leakage almost unaffected lt 0.1 s

25
Behaviour of optical parameters during combined
squeeze of IR1 and 5 - II
Critical region for Beam 2 smoothing should
improve it
26
Behaviour of optical parameters during combined
squeeze of IR1 and 5 - III
Critical region for Beam 2 smoothing should
improve it
27
Status of squeeze optics for IR2 and 8

• As far as the other insertions are concerned
• IR8
• it is foreseen to be squeezed down to beta 2 m
  (1 m is excluded due to aperture issues).
• Optics files present, but not optimized, yet
  (quadrupoles variation not smooth enough). Once
  the optical solutions will be in final form, the
  approach presented should be repeated. The
  crossing scheme needs also to be implemented
  during the squeeze.
• IR2
• it is foreseen to be un-squeezed for protons and
  squeezed down to beta 0.5 m for ions.
• Optics files for the un-squeeze are still
  missing, while those for the ions are available.
  In both cases the crossing scheme needs to be
  computed.
• IR2 and 8 transition from beta 10 m and MQX
  strength from 220 T/m to 205 T/m.

28
Summary and outlook

• MADX tool developed to qualify the squeeze.
• Ramping with constant optics (injection) up to
  7TeV is feasible (for IR2 and 8 it will depend on
  performance of triplet quadrupoles).
• Ramping with constant crossing scheme (injection)
  up to 7TeV is problematic for IR2 (to be
  re-computed) and thigh, but feasible for IR1, 5,
  and 8.
• Strength issues will not impose the choice of
  when to change optics/crossing scheme.
• Squeeze with one insertion at a time (IR1 or 5)
  is not an issue in terms of optical parameters
  (and for a perfect machine).
• Impact of errors to be assessed.
• Behaviour of Beam 2 to be analyzed in details
  (possibly fixed by smoothing transition between
  beta 1 m and 2 m).
• Squeeze with both insertions at a time (IR1 and
  5) is feasible, provided situation of Beam 2 is
  fixed.
• Optics squeeze of other insertions (IR2 and 8) to
  be computed/finalized. Their contribution should
  be assessed.
• Transition from injection to collision crossing
  scheme to be studied.