DR dipole (15 deg)

A new 15 deg bend magnet was designed to operate at higher beam energy and to minimize higher order multipoles.

Design

Modeling TN JLab-TN-19-041 media:19-041.pdf

ME drawings (square wire, Feb 11, 2020)

- Dipole fixture media:200KeVYDipoleFixture-JL0087295.pdf

- Dipole winding media:200KeVYDipoleCoil-JL0087835.pdf

Shims

- media:MDR_shim.pdf

- Laminate shim stock (2 mil * 31 layers = 0.064 mil thick laminate)

- 28 mil shim for 1.688 deg (top 0.844 deg cw, bottom 0.844 deg ccw); each 2 mil layer will change the angle by 0.048 deg (e.g. 30 mil reduces angle to 1.640 deg, or 26 mil increases angle 1.736 deg)

- We have 6 shims on hand, that is, we may choose up to 6 angles

Fabrication

Milhous was awarded fabrication of two DR magnets (four halves).

• Oct 5, 2020 (M. Beck) First half received from Milhous last week. The dimension inspection of the aluminum coil fixture is correct. Electrical testing, hipot and surge testing at 500V is completed, all meet JLAB acceptance criteria. Can not confirm turn count is correct with this kind of winding process and there is no additional coil to conduct coil comparison testing. It might be reasonable to assume the wire count is correct as we only have one halve section and no mapping can occur until we receive the next halve. Coil appearance looks reasonable for the fashion used for fabrication/winding. We just need 3 more halve sections to put these magnets together, after QA is completed on the additional 3 articles we will begin mapping. Milhous winding another half, will shop to JLab ASAP, within a week or so

Measurments

• MMF measurements of DR001 - media:Dipole_15deg_DR001_FieldMap.txt
• MMF measurements of DR002 (installed at CEBAF) - media:Dipole_15deg_DR002_FieldMap.txt
• Riad's analysis of the two dipoles - media:Dipole15deg_FieldMap.pptx

(January 13 2021 - MMF coil measurements)

Magnet DR01

TOP-SN#01 L/60Hz=1.617mH DCR=915.9 milliohm BOTTOM-SN#02 L/60Hz=1.563mH DCR=887.1 milliohm

Magnet DR02

TOP-SN#03 L/60Hz=1.527mH DCR=881.5 milliohm BOTTOM-SN#04 L/60Hz=1.540mH DCR=887.3 milliohm

From Jay - The ratio of inductances suggests a 1.7% turns discrepancy while resistance suggests 3.2% top vs bottom in DR01. (inductance goes as N^2, resistance as N). I suggest using the DR02 in the machine.

Intermediate design exchanges

Archive of intermediate drawings

Oct 18, 2019 - Final 15 deg coil fixture

• Drawing media:191018_15_COIL_FIXTURE.pdf

Specifications and markup documents

Oct 23, 2019 - Jay mark-up for low- and high- energy coil

• Drawing media:191023_Jay_dwg_markup.pdf
• Specification media:191023_Jay_spec.docx