Accelerator targets design - The challenge of high power density. Ido Silverman DAPNIA visit 24/10/07

Transcription

1 Accelerator targets design - The challenge of high power density Ido Silverman DAPNIA visit 24/10/07

2 Layout SARAF High power targets design High heat flux cooling Examples SARAF beam dump LiLiT Palladium target 2

3 SARAF Nuclear research with neutrons and primary beam Production of radio-isotopes for medical applications 3

4 High power targets design Material issues (high temperature, high radiation dose) High heat flux Thermal stress Safety!!! 4

5 q [kw/cm 2 ] High heat flux cooling Pool Boiling Burnout (H 2 O) Jet CHF (Large radius) Extremely High Heat Fluxes Tube Flow CHF Microchannel Cooling Heat Pipes Jet Impingement (Stagnation zone) Logical Oxyacetylene Circuits Torch Power Transistors Fission Reactors High Power Microwaves Solar surface Fusion Reactors YAG Cutting Lasers TIG Plasma Arc Highest to Date 35 [kw/cm 2 ] 2.7 [kw/cm 2 ] 40 [kw/cm 2 ] CO 2 Cutting Lasers 5

6 Example Phase A SARAF beam dump Simple and safe solution No size limitation Long exposure time Very low activation limit with 100% beam loss 2-10 MeV protons and deuterons 6

7 SARAF beam dump - Activation The heat removal design of the beam dump necessitate use of material which can be machined This material should minimize prompt radiation and activation at beam energies of < 10 MeV Prototype I heavy metal (97% W) Current design Tungsten over copper backing 7

8 SARAF beam dump cm D-plate 4 jaw slit beam dump A layout of the BD arrangement. The beam enters from the left side. 8

9 Mini-channel cooling 9

10 20 kw p/d Heavy metal dump HM front HM back cooling channels assembly on e gun SS cooling flange 10

11 Mini-channels cooling capability Temperature [C] TC1 TC4 q" Beam power density [W/cm2] Time [s] 0 11

12 Micro-channels cooling capability 12

13 Examples - LiLiT High power Liquid Lithium Target 4 10 kw beam power R rms = mm Design issues Surface shape Be-7 Li boiling and generation of bubbles 13

14 ANL Li target design D = D = R= D = D = W x D D = = 2.00 x 0.25 (cm) J. Nolen RSI 2005 D = Operat ing 7.21 D = 6.00 St at ic 8.31 D = W x D W x D 3.00 = 3.75 x 3.75 = 3.75 x W x H x N = 1.00 x x 3 14

15 LiLiT preliminary design Containment chamber Flowmeter Secondary target location Beam line EM Pump Cold trap Li Vacuum pump Heating/Cooling system 20 kw Storage Ar 15

16 Nozzle design beam Water jet 16

17 Conceptual design beam W. Gelbart ASD Inc. 17

18 Example Palladium target Motivation 103 Pd is commonly used radioisotopes for treating prostate cancer Current irradiation techniques suffer from: low production rates due to target cooling limitation difficult electroplating process to prepare the target Method Use of high heat flux liquid metal (LM) jet impingement cooling technique Make target of self-supporting thin Rhodium foil Use the 103 Rh(d,2n) 103 Pd reaction with deuteron beam of MeV 18

19 Palladium target proposed design 2 ma, 20 MeV D beam 30x60 mm Elliptic target 180 µm Rh foil Target to beam angle of 30 o Maximum heat flux from target 6.2 kw/cm 2 Calculated maximum foil temperature < 300 o C 2 ma, 20 MeV, D beam 60 mm 30 mm 30 o Target foil Temperature [C] Coolant Cooled surface Heated surface Calculated foil temperature, one cooling jet Coolant out Coolant in R [mm] 19

20 LM cooling loop Schematic drawing of the experimental liquid-metal cooling system The jet impingement cooling head and details of the target disk The liquid metal jet impingement cooling system during a vacuum test I. Silverman et al. NIM B 241(2005)

21 High power cooling with LM I. Silverman et al. NIM B 261(2007)747 21

22 High power cooling with LM 22

23 Rh foil strength 250 µm thick Rh foil has been demonstrated to be strong enough to hold the expected LM cooling system pressure for several days, even at the high temperature calculated to exist during the irradiation process Foil thickness * Temperature Pressure Test time Breaching [µm] [C] [atm] [hr] * Foil dimensions: Race track, 100x12 mm 23